Sensation and Human Potential

You fill up my senses / Like a night in a forest / Like the mountains in springtime / Like a walk in the rain / Like a storm in the desert / Like a sleepy blue ocean/ You fill up my senses/ Come fill me again

Annie’s Song by John Denver

The Importance of Sensation and Perception

Eat, survive, reproduce. Whether one lives in the rainforest or an urban metropolis, survival requires locating and identifying edible foods and avoiding predators. In Chapter 2, we examined how our nervous system evolved to enable us to address these basic survival needs and how our brain evolved to enable us to consider “what’s it all about?” In this chapter, we consider how our nervous system transmits and interprets sensory information, relaying it to parts of the body capable of responding. Sensation refers to the initial detection of a stimulus resulting from the physical stimulation of a receptor in a sense organ (e.g., eye, ear, etc.). Perception refers to the integration and interpretation of sensory information. Often sensation is described as a bottom-up process, starting with stimulation of a sense organ receptor and moving toward the brain. In contrast, perception is often described as being a top-down process since the initial integration and interpretation takes place in the brain. The importance of sensation and perception to individual and species survival is undeniable.

Sensation – Detecting Stimuli

Even very simple organisms possess the ability to sense and respond to environmental stimulation. For example, moths are attracted by light. Aristotle referred to five human senses: seeing, hearing, taste, smell, and touch. Others consider there to be additional senses of temperature (thermoception), pain, muscle tension (kinesthesia), and balance (equilibrium). Each sense responds to a specific type of physical stimulation and possesses specific receptor cells. Figure 3.1 lists the stimulus, sense organ, and receptor for the different senses.

Sense	Stimulus	Sense Organ	Receptor
Vision	Light waves	Eye	Rods and cones of the retina
Hearing	Sound waves	Ear	Hair cells of the basilar membrane
Taste	Edible substances	Tongue	Taste buds of the tongue epithelium
Smell	Odorous molecules	Nose	Smell receptor of the nasal epithelium
Touch	Tactile stimulus	Skin	Touch receptors
Temperature	Heat and cold	Skin	Thermoceptor of skin
Pain	Intense mechanical, thermal, or chemical stimulus	Skin	Pain receptor of skin
Balance and muscle tension	Position of muscles, joints, and tendons	Ear, skeletal muscles, joints, tendons	Hair cells of the semicircular canals, nerve endings of the muscles, joints, and tendons

Figure 3.1 The senses

Evolution of Sensation

Sensory information, to the extent that it accurately represents the environment, improves adaptation (Gaulin & McBurney, 2003). It should not be surprising that sense organs exist in very simple animals or that more than half the human brain is dedicated to the reception and interpretation of sensory information. Vision enables humans as well as less complex organisms (e.g., insects, sea crabs, birds, etc.) to avoid bumping into objects and to identify food sources. Hearing enables animals to detect the presence and location of dangerous or appetitive objects at a distance. Taste and smell enable us to detect potential foods or poisonous substances. Touch and pain indicate the presence of potentially dangerous objects or conditions (Gaulin & McBurney, 2003).

It is possible to study how the human brain evolved to detect, transmit, and interpret sensory information by studying the brains of other animals, especially primates (and particularly monkeys (Kaas, 2008). In comparison to our earlier mammalian ancestors, primate sensory and motor systems are much more complex and divided into a large number of functional units. For example, macaque monkeys possess between 30 and 40 separate cortical areas dedicated to vision and 15 to 20 areas dedicated to hearing. The human brain is approximately 15 times the size of the brain of macaques, possessing approximately 100 billion neurons in comparison to 6.4 billion neurons and over 200 cortical areas. Early primates were small, nocturnal, lived in trees, and ate insects, buds, and fruit. Their eyes were forward-looking and large, implying that vision played an important adaptive role in their survival. The increased number and size of cortical areas dedicated to vision, and increased number of motor areas, enabled coordination of visual information with reaching for and grabbing food while suspended from unsteady tree branches (Kaas, 2008).

Figure 3.2 Tree dwelling primate

Sensory Thresholds

The first scientific studies of human sensation and perception were conducted at the University of Leipzig where Wundt later established the first psychology laboratory. This earlier research obviously influenced Wundt’s proposed definition, goals, and methods for the discipline. In 1860, Gustav Fechner published the classic “Elements of Psychophysics”, naming the systematic study of the effect of varying the properties of stimuli on sensation and perception. Fechner extended the prior work of Max Weber examining the initial step enabling perception; detecting the presence or change in value of a stimulus. Weber distinguished between these two types of sensory thresholds. An absolute threshold is the minimum intensity of a stimulus required for one to detect its presence. For example, how bright does a light have to be or how loud does a tone have to be for a person to notice it. A difference threshold (often referred to as the “just noticeable difference” or jnd) is the minimum amount of change in intensity required for a person to notice a difference. Fechner replicated Weber’s findings that the amount of change required is a constant fraction of the comparison stimulus. For example, if the constant jnd for length is one-tenth, you would need to increase a 10-inch line by one inch and a 20-inch line by two inches to notice the difference. This relationship is known as “Weber’s Law.”

Adaptation requires detecting changes in one’s environment and behaving in a way which promotes survival. Clearly, one is at a disadvantage if a sense is not functioning optimally. If you ever had your hearing tested, the technician probably used one of the two procedures developed by Weber, the method of limits or the method of constant stimuli. Using the method of limits to determine an absolute threshold, the amplitude (i.e., loudness) of a sound would be gradually increased until you report hearing it. Then the amplitude would be decreased until you report no longer hearing it. This would be repeated several times for different frequencies of sounds, from very low bass to very high treble.

Usually, we think of a single value as determining an absolute or difference threshold. That is, a sound must reach a particular decibel level (loudness) for us to sense its presence. Unfortunately, when testing is conducted, one does not always obtain the same result. This raises the question of how to define what constitutes “the” (apparently not so absolute) threshold? Is it the value where you first report hearing the sound? Or, is it the value where you always report hearing it? Early on, researchers decided to compromise between these two possibilities. The (not so) absolute threshold is defined as the average of the points at which the sounds appeared and disappeared.

A similar process would be followed to determine a difference threshold. In this instance, the technician would start with a sound you could hear and gradually increase the amplitude until you reported it being louder. Then the amplitude would gradually be decreased until you reported it being softer, etc. The jnd would be defined as the average change required for you to report the tone as being louder or softer.

A problem with the method of limits is that people sometimes anticipate hearing a stimulus appear or disappear. In order to address this problem, the method of constant stimuli presents sounds at random amplitudes. Unfortunately, the result frequently changes from trial to trial. That is, in testing for an absolute threshold, sometimes the person will report hearing it and sometimes not. So much for absolutes! Weber defined the absolute threshold as that value which the individual reported hearing 50 percent of the time. Similarly, a jnd was defined as the amount of change required for you to report a difference half the time. These procedures and criteria continue to be used for research and diagnostic applications.

Threshold values change as the result of continual exposure. This phenomenon is called sensory adaptation. With the exception of pain and extremely intense stimulation, the nervous system becomes decreasingly sensitive to prolonged events. For example, if someone holds your hand you stop feeling it after a little while. You quickly adapt to hot showers and to the cold when you jump into a pool of water. The same is true after exposure to perfume or after-shave lotion, or to constant background noise (e.g., the sound of a fan). From an adaptive perspective, it is as though once you have detected the presence of a stimulus it is not essential to maintain the same level of sensitivity.

Vision

Every man takes the limits of his own field of vision for the limits of the world.

Arthur Schopenhauer, Studies in Pessimism (1851).

Whether adapting to the rainforest or a modern city, we rely heavily on vision to survive and enjoy our surroundings. From the time we wake up in the morning to the time we go to bed at night, we almost constantly process and respond to visual information. We move about our surroundings, locating needed substances and objects, constantly assessing achievement of our goals. We fashion and use tools tailored to the demands of our unique environmental niches. Examples include blowpipes in the rain forest and laptops in our schools. No matter where they reside, humans engage in creative arts. Examples include playing flutes and fashioning necklaces in the rainforest; and playing flutes and fashioning necklaces in cities. The more some things change, the more they stay the same! We gaze upon and pay close attention to the appearance of others as we interpret facial expressions and body language in our interpersonal interactions. As expressed by Schopenhauer, our interpretation of our world and life is based upon what we see.

For most of our history on earth, humans experienced daily changes in the amount of light based upon the position of the sun. Only in the light do we experience the beauty of color. Seeing in the dark is a very different and more challenging experience. We will review how our eyes detect and process reflected light to enable color perception, and adapt to different levels of illumination. Transduction refers to the process through which physical stimulation is converted into neurological action potential and transmitted from receptors to higher brain regions for further processing. Figure 3.3 shows the major parts of the eye involved in the transduction process converting light into electronic signals transmitted to the brain. Light reflected from objects enters and undergoes initial focusing as it passes through the transparent cornea. Depending upon darkness or brightness, the iris dilates or closes, controlling the amount of light reaching the lens. The lens changes shape depending upon distance of the object, completing focusing. The remaining focused beam of light reaches photoreceptors lining the surface of the retina. Most of the light reaches the center of the retina, with the fovea being the small focal point with the greatest concentration of photoreceptors. Signals from the photoreceptors travel along nerve fibers to the optic nerve at the back of the eye. From there the signals are transmitted to the occipital lobe of the cerebral cortex.

Figure 3.3 The Human Eye

Color Vision

Can you imagine the world without color? Figures 3.4and 3.5 demonstrate not only the beauty which would be missing, but also the amount of potentially adaptive information. It is far easier to identify similarities and differences or look for a particular feature with the added dimension of color. This is even true for the birds and the bees, both of which possess excellent color vision. Clearly this ability is valuable from an adaptive evolutionary perspective.

Figures 3.4 and 3.5 The birds the bees

The psychophysics of color perception is non-intuitive. Subjectively, color differences seem qualitative rather than quantitative. That is, blue, green, and red are perceived as different in kind rather than different in magnitude on a dimension. You may be familiar with the acronym Roy G Biv. It stands for red, orange, yellow, green, blue, indigo, and violet. This is the reverse order of these colors on the electromagnetic wavelength dimension which extends from infinitesimally small gamma rays (measured in fractions of nanometers, billionths of a meter) to TV and radio waves which can extend for thousands of meters (see Figure 3.6).

Figure Figure 3.6 The electromagnetic spectrum

The retina contains photoreceptors sensitive to a very narrow range of wavelengths, approximately 400 nm (violet) to 700 nm (red). The retinal surface includes two types of photoreceptors called rods and cones based on their shape. Rods are very sensitive to light and serve as the basis for vision in the dark, however visual acuity is poor in comparison to during daylight. Since rods are monochromatic (i.e., respond to only one color) and the information cannot be combined with information from cone receptors, very limited color perception is possible in the dark. There are three types of cones activated during daylight, each enabling perception of color on limited sections of the visible part of the electromagnetic spectrum: those responding to short (bluish), medium (greenish), and long (reddish) wavelengths (see Figure 3.7).

Figure 3.7. Rods and cones

The trichromatic theory of color vision, first advanced by Young (1802) and elaborated upon by Helmholtz (1850), proposes that all the colors humans perceive result from combinations of the outputs of photoreceptors for three primary colors (see Ypu Tube video). It was not until a century later that existence of the three types of cone cells was confirmed (Svaetichin, 1956), providing support for trichromatic theory.

Hering (1892) challenged trichromatic theory based on the observation that it does not seem possible to combine certain colors. There is no problem imagining reddish-orange, yellowish-green, or greenish-blue, but one cannot imagine reddish-green or bluish-yellow. For this reason, Hering proposed the opponent-process theory of color vision. The theory proposes that there is an achromatic (i.e., without color) brightness system and a color system based upon the combined results of red-green and blue-yellow opponent channels. Stimulation of one of the colors of an opponent pair is presumed to inhibit perception of the other. This is how the theory explains the inability to combine red and green or blue and yellow. Another phenomenon that can be explained by opponent-process theory but not the trichromatic theory is the negative afterimage (see Figure 3.8). Stare at the word “afterimage” in the center of the rectangle below for 30 seconds. If you then shift your gaze to a white surface you will see the letters and background comprised of the compliments of the original colors. This is what would be expected if the initially activated component of a red-green or blue-cell system became fatigued. The result would be an illusion consisting of the complementary color.

Figure 3.8 Negative afterimage.

We now know that whereas the trichromatic theory of color vision is correct at the level of the cones, the opponent-process theory is true at later stages of processing in bipolar cells on the way to the optic nerve (see Figure 3.8).

Figure 3.9 Opponent-process retinal receptor cells

Adapting to the Dark

Figure 3.9 shows the change in threshold intensity (i.e., the amount of light needed) to see in the dark over time for rods and cones. The cones are much more sensitive to light during the first five minutes but do not increase in sensitivity beyond ten minutes. Dark adaptation continues to improve with the trajectory for the rods leveling off after another ten minutes. This produces the scallop in the figure labeled the rod-cone break.

Figure 3.10 Dark adaptation

Hearing and other Senses

Hearing

The exhilarating ripple of her voice was a wild tonic in the rain.

Scott Fitzgerald, The Great Gatsby

Humans rely heavily on hearing as well as vision to survive and enjoy our surroundings. Sound can help us detect the presence of and locate objects which are at great distances or out of sight. Speech communication relies on the ability to hear. If you are similar to most college students, you spend a considerable amount of time listening to music. As expressed by Fitzgerald, the voice of a loved one can soothe and exhilarate us.

Our ears detect and process the vibrations produced by sound waves. When graphed, the amplitude (loudness) of a sound is indicated by the height from top to bottom of a wave cycle. The pitch (low bass vs. high treble) is a function of the frequency of waves per unit of time (see Figure 3.11).

Figure 3.11 Amplitude and frequency of sound waves.

Loudness is measured in decibels. Figure 3.12 shows the decibel levels of some common events. Please be careful about exposing yourself to loud sounds. It is possible to permanently damage your hearing by prolonged exposure to loud music, whether at concerts or when listening with headphones.

Figure 3.12 Decibel Levels of Common Events.

Figure 3.13 shows the major parts of the ear involved in the transduction process converting sound waves into electronic signals transmitted to the brain, primarily the temporal lobe of the cerebral cortex.

Figure 3.13 Anatomy of ear (brown is outer ear, red is middle ear, purple is inner ear).

The ear can be divided into outer, middle, and inner parts. The outer ear includes the ear flap, ear canal, and eardrum. The middle ear is in an enclosed chamber behind the eardrum and includes the three tiniest bones (ossicles) in the body often described as the hammer, anvil, and stirrup. The inner ear consists of the cochlea, a snail shaped tube filled with fluid. When sound waves reach the eardrum they cause it to vibrate. These vibrations are amplified by the ossicles and transmitted to the cochlea. The limits of human hearing are determined by the nature of tiny hair cells contained within the basilar membrane lining the cochlea (see Figure 3.14). Starting at the end (apex) of the cochlea, the hair cells are responsive to increasing frequencies of sound waves. Human hearing extends approximately from 20 to 20,000 Hz (vibration cycles per second). The neural information from the basilar membrane is transmitted to the auditory nerve and then to the brainstem.

Figure 3.14 The cochlea.

Smell and Taste

One of the very nicest things about life is the way we must regularly stop whatever it is we are doing and devote our attention to eating.

Luciano Pavarotti and William Wright, from Pavarotti, My Own Story

Figure 3.15 portrays the different cells for salty (Type I), sweet, umami (flavor of glutamates) and bitter (Type II), and sour (Type III) tastes. Figures 3.16 and 3.17 show the neural pathways for the senses of taste and smell. The surfaces (epithelium) of the nasal passage and tongue contain receptors sensitive to specific odors and tastes. Stimulation of the smell and taste receptors transmit signals terminating in the temporal lobe of the cerebral cortex. The senses of smell and taste are not as fundamental to human survival as vision and hearing. Still, they play an important adaptive role in the identification of poisonous foods and chemicals. Eating is also one of the basic pleasures of life. Smell and taste work in concert in helping us discriminate flavors and enjoy the spices of life.

Figures 3.15 and 3.16 Neural cells and pathway for sense of taste.

Figure 3.17 Neural pathway for sense of smell.

Touch, Temperature and Pain

Figure 3.18 portrays the different specialized skin receptors for touch, temperature, and pain. Information from these receptors is relayed to the primary somatosensory area of the parietal lobe in the central cortex.

Figure 3.18 Skin receptors for touch, temperature, and pain.

Two-point discrimination thresholds for the sense of touch vary according to the amount of brain space dedicated to the body part in the somatosensory cortex (see Figure 2.2). The fingertips and lips which have disproportionate amounts of brain space are the most sensitive areas, typically requiring only 2-4 mm for one to be able to report being touched in two different spots. In comparison, it might take from 10-15 mm on the palm of one’s hand or 30-40 mm on one’s back to detect being touched in two different spots.

Sherrington (1906) was the first to demonstrate that certain types of intense stimulation could elicit reflexive responses and responses by the autonomic nervous system along with the sensation of pain. When a high threshold is reached for mechanical (intense pressure or injured tissue), thermal (extreme heat or cold), or chemical (toxins) stimulation, a neural signal is transmitted to the central nervous system. A stimulus likely to result in injury will elicit a withdrawal reflex at the level of the spinal cord within half a second (see Figure 3.19).

Figure 3.19 Spinal reflex arc.

Balance and Muscle Tension

Animals, including human beings, are able to perform amazing feats of balance. These feats require coordination between the vestibular system in the ears, the eyes, and proprioception (i.e., sense of muscle location and movement). Attached to the cochlear in the inner-ear (see Figure 3.12) is a pretzel-like structure called the semi-circular canals. The three circles are filled with fluid and contain hair cells which respond to the position of and speed of movement of the head in three-dimensional space. This information is transmitted to the thalamus and parietal lobe of the cerebral cortex. There it is combined with information obtained through the eyes regarding the body’s position in space and sensors of the muscles and joints. Integration of this information enables us to maintain our balance while stationary or in motion.

A common test to determine whether your proprioceptive sense is functioning properly is to see if you can touch the tip of your nose with your eyes closed. This would only be possible if you are receiving accurate non-visual information regarding the location of your body parts (see Figure 3.20).

Figure 3.20 Proprioceptive receptors.

Sensation and Human Potential

Our senses helped humans to survive on earth under very different geographic and climatic conditions for tens of thousands of years. For practically all of this time we lived as nomadic hunter-gatherers. It is only within the past 11,000 years that domestication of plants (i.e., agriculture) and large animals permitted production of sufficient food surpluses to remain in one location (Diamond, 2005). This eventually led to establishing larger and larger social units, starting with bands and tribes, eventually becoming chiefdoms and states (Diamond, 2012). Recalling the picture of Manhattan, it is only within the past 400 years that the scientific method has resulted in technologies substantially transforming the human condition. Prior to then, we adapted to the environmental conditions under which we biologically evolved. Now we must adapt to a human-constructed environment. This technology-enhanced world frees us from dedicating our lives to fulfilling basic survival needs. We are able to contribute to our social units in an increasing variety of ways. At the same time, technologies have resulted in dangers for which we are not genetically prepared. Some of these dangers result from limitations of our senses. For example, industrialization resulted in production of carbon monoxide, a gas which did not previously exist on earth. Humans cannot smell carbon monoxide, resulting in many accidental deaths from exposure.

Technological enhancements of our senses (primarily vision) were essential to much of the progress occurring over the past 400 years. It is common to refer to Galileo when discussing the beginning of the scientific revolution. One of the ways in which sciences progress is by developing instruments permitting the observation of new natural events. Galileo used a telescope to discover four of Jupiter’s moons. The observation that these moons revolved around Jupiter and not the earth was inconsistent with the prevalent belief that the earth was the center of the universe. Although extremely controversial at the time, it is now impassionately accepted that the earth revolves around the sun rather than the other way around. Key to Galileo’s observations and conclusions was the ability to see objects not visible to the naked eye. Much of the scientific knowledge acquired since Galileo’s time has required similar enhancements of our senses. Examples include the microscope and amplification of sound. It is fascinating to consider the possibilities for enhancement of human senses and performance along with the ethical implications (Khushf, 2005).

Perception and Human Potential

The beginning of human knowledge is through the senses, and the fiction writer begins where human perception begins.

Flannery O’Connor

Perception – Interpreting Stimuli

We have completed consideration of the stimulation processed through Aristotle’s five major senses along with balance and movement. At this point the body has received input that something has happened in an exclusively bottom-up process. With the exception of painful stimuli posing immediate danger triggering a spinal withdrawal response, sensory information is relayed to the brain for further processing.

Not all environmental stimulation relates to survival or achievement of one’s goals. Adapting to one’s environment requires interpretation and prioritization. Once an event is detected, it is important to determine where it originated and what it is. One way the brain has evolved to interpret and prioritize sensory input is the development of feature detectors (Hubel and Wiesel, 1959, 1962). These are cells in the visual cortex which respond to stimuli likely to convey adaptive information. Specialized cells have been discovered for movement, lines, edges, and angles. These characteristics are frequently associated with biologically significant stimuli. For example, movement might signal the presence of a predator. Lines and edges could signal the presence of solid stationary objects or a sudden drop off in height. As shown in Figure 3.21, even infants and other animals are cautious upon approaching a visual cliff (Gibson and Walk, 1960).

Figure 3.21 The visual cliff.

Depth Perception

The ability to perceive depth (the relative location of objects) and distance (how far objects are from you) in three-dimensional space is essential to survival and responsible for the visual cliff. In addition to feature detectors for edges and lines, there are additional visual cues which facilitate depth perception. Some of these are dependent on the information obtained from both of our eyes (i.e., binocular cues) whereas others are based upon the information available to one eye (i.e., monocular cues). Not all animals with two eyes have them located so that they are facing in the same direction (e.g., fish). When both eyes face forward there is overlap as well as differences in the visual fields providing potential information regarding the location of objects. The human visual field covers approximately 200 degrees of which there is 120 degrees of overlap between the two eyes.

The major binocular cues are retinal disparity and convergence. Retinal disparity results from your eyes being separated in space, producing stimulation from slightly different angles. The stimulation from objects which are far away is much more similar for both eyes than the stimulation from close objects. Similarly, your two eyes converge (i.e., move closer to each other) as objects move closer. This provides depth and distance information from the muscles controlling eye movements.

It is counter-intuitive but most of the cues related to perceiving objects as three-dimensional are monocular and two-dimensional. Artists take advantage of such cues in creating realistic images. The major monocular cues are linear perspective, occlusion (interposition), textual gradient, relative size, size familiarity and position relative to the horizon (Figure 3.22).

Figure 3.22 Monocular depth cues.

Gestalt Principles of Perceptual Organization

As described in Chapter 1, the Gestalt psychologists believed that perception was primarily a top-down process involving meaningful units rather than a bottom-up process combining elements of sensation. Only a process including the effects of prior experience could meaningfully interpret often ambiguous sensory information. Determination of what constitutes the figure and ground in an image provides an example. The images in Figures 3.23 and 3.24 may be perceived in two ways. The first may be perceived as either a black vase on a white background or two white heads facing each other on a black background. The second image may be seen as either a saxophone player on a white background or a face on a black background. Ordinarily you will see one of the two possibilities and not the other. Once informed of the other possibility one may cycle back-and-forth between the two perceptions demonstrating the impact of prior experience upon the organization and interpretation of sensations. Another way of influencing interpretation of an ambiguous image is to establish a perceptual set through exposure to conceptually related images or words. For example, if you first saw pictures of a table and a chair, or read the words “table” and “chair”, you would be more likely to perceive the vase than the faces. If you saw pictures of an arm and leg or read the words, you would be more likely to perceive the faces. The establishment of a perceptual set is a clear cut example of top-down processing of sensory information.

Figure 3.23 and Figure 3.24 Faces or vase? Saxaphone player or woman?

Another example of top-down processing involving prior experience is perceptual constancy. This refers to the fact that an object’s shape and size is perceived as remaining constant despite differences in orientation and location (see Figure 3.25).

Figure 3.25 Constancy of shape and size.

The Gestalt psychologists proposed several principles to account for the organization and perception of groups comprised of ambiguous elements. Their major principles include proximity (Figure 3.26), similarity (Figure 3.27) and closure (Figure 3.28). You are likely to perceive the first drawing as consisting of alternating blue and black rows, the second as pairs of lines in three columns, the third as four curved lines consisting of four dots and the fourth as a complete circle and square.

Figures 3.26 – 3.28 Principles of proximity, similarity and closure.

Learning to read is an excellent example of the importance of Gestalt principles. Reading may be described as a sequence of steps establishing larger and larger meaningful units (i.e., gestalts). Eye-movement recordings reveal that individual letters are not initially perceived as units. With increased experience, we are able to integrate the components into a relatively small number of distinct letters followed by integration of letters into words. It has recently been demonstrated that we perceive the letters of words simultaneously (i.e., as a “gestalt”) not sequentially (Adelman, Marquis, and Sabatos-DeVito, 2010). Eventually, we are able to read aloud fluently by scanning phrases and sentences (Rayner, 1998). The role played by experience and top-down processing in the interpretation of letters is exemplified by the ambiguous second letters below. The first letter is usually perceived as an “H” and the second as an “A” (Figure 3.29).

Figure 3.29 Gestalt principles of perceptual organization and reading.

Arguably, reading is the most important skill one can acquire to adapt to the modern human condition. We describe the elementary-school experience as emphasizing the three “R”s (reading, “riting” and “rithmatic.” “Reading is fundamental” in that it is essential to learning to write and acquiring quantitative concepts. The importance of reading will be considered further in Chapters 6 (Indirect Learning) and 8 (Developmental Psychology).

College As Education of your Senses

As described in Chapter 1, the college curriculum is designed to help you develop different perspectives with which you can understand and appreciate your life. Usually undergraduates take a course in art, music, or both. Such courses might be considered “education of the senses.” The fact that even bands of nomadic hunter-gatherers produce art and music suggest that there is something about our genetics which makes such activities intrinsically rewarding. In Chapter 4, we will discuss the role of motivation and emotion in realizing our potential as individuals and a species. Certainly, a developed appreciation of the different forms of human creativity enhances and enriches our lives.

College courses in art and music expose students to classic and current forms of human creativity. In the same way that reading requires constructing larger and larger “gestalts” (i.e., letters, words, phrases, sentences, etc.), the same can be true for art (lines, shapes, forms, patterns, etc.) and music (e.g., tones, chords, melodies, etc.). Your eyes and ears can be “trained” to detect elements and patterns of visual and auditory sensations. Courses in art and music analyze (i.e., determine the common elements of “good” art and music) and synthesize (i.e., relate different examples of art and art forms to each other) the creative and performing arts. In this way, such courses convey our current understanding of those defining human qualities which do not at first glance appear related to eating and surviving but rather to “What’s it all about?”

There is a saying that you get out of life what you put into it. The amount of time and effort you dedicate to any activity will influence how proficient you become. This applies to your schoolwork and grades, but the college experience provides other possibilities for developing your potential. There are usually many extra-curricular activities available for you to sustain existing hobbies and interests and explore new ones. At the end of the next chapter, I will describe a strategy for objectively describing your current self and ideal self. This will provide an opportunity to engage in soul-searching concerning the knowledge, skills, and attitudes you would like to acquire in your immediate and long term future. For now, I will restrict the discussion to activities related to sensation and perception. Colleges and universities frequently have clubs or activities dedicated to art (vision), music (hearing), food and/or wine tasting (taste and smell), dance and gymnastics (balance). There are often offices or campus units where you can obtain paid or voluntary positions requiring specialized applications of your senses. This would certainly be true if you worked as an artist for a campus newspaper or as a DJ for a college radio station. There is an old saying that there are three types of people: those who make things happen, those who watch things happen, and those who ask, “What happened?” In the same way that it is important to be an active student by trying to anticipate and answer questions based upon your course material, it is important to be active in your personal development during your college years. Try to explore your college environment, searching for growth opportunities. Try out and join interesting clubs. Attend special lectures and events. Make things happen!

Things do not happen. Things are made to happen.

John F Kennedy

Self-Control Projects to Educate your Senses

At the end of Chapter 1, I listed several recent self-control projects conducted by my students. Scattered among them were projects designed to increase and improve drawing and piano playing. As an example of how the psychology research literature can assist you in achieving your personal objectives, an experiment was conducted to compare two different approaches to learning to play the piano. It was found that practicing with both hands at the same time was better and more efficient than practicing with one hand at a time (Brown, 1933).

The psychology research literature can also play a valuable role in your self-control project. One of the skills a professional in any field must possess is the ability to locate and evaluate research. We live in a time in which we are inundated with information from the media and the internet. Reviewing the literature can feel like searching for a needle in a haystack. Even when you think you have located relevant information, how can you be certain you can trust the source? Fortunately, most professions attempt to facilitate this process by developing peer-evaluated databases. The American Psychological Association produces PsycINFO, which lists and abstracts peer-reviewed articles dating from the 1800s. In addition to psychology research, PsycINFO covers related fields such as medicine, neuroscience, and social work. Most college libraries will have a subscription to this extremely helpful and credible database.

Evolution: Adaptation through Natural Selection

Mostly Nature

As we move along in the book, I will frequently try to relate the current material to major themes described in Chapter 1. I will ask you to periodically recall Maslow’s pyramid of human needs, the video of the Nukak tribe in the rainforest, and the transformation of New York City over the course of two centuries. Despite the inventions and technological innovations of the relatively recent past, there are still people living the nomadic Stone-Age lifestyle which characterized the human condition for almost our entire time on this planet. What made it possible and what was necessary in order for this transformation to occur?

We share many basic needs and behavior with other species. We all inhabit a planet replete with edible foods, predators, and potential sexual partners. Unless we continue to eat adequately, successfully avoid and/or escape from predators, and mate, we will not survive as individuals or as a species. In order to eat, survive, and reproduce, we need to be able to sense food and danger, identify receptive mates, and respond in an adaptive manner.

The Mostly Nature section addresses how our physical structure impacts upon our ability to survive and realize our potential as individuals and a species. In Chapter 1, we reviewed how our contemporary approach to psychology integrated the interests and goals of the early schools. This will be reflected in the chapters which comprise this section of the book. The earliest school, eventually named structuralism, was primarily concerned with our internal world consisting of sensations, images, and feelings. In Chapter 3, we will review the structure and function of our sense organs for external stimuli (e.g., our eyes for vision, ear for hearing, etc.) addressing how experience results in combining stimulus elements into meaningful patterns (i.e., gestalts). The functionalist school was concerned with how our internal world enabled us to adapt to our external world. Chapter 4 reviews how we process and eventually respond to internal stimuli (e.g., hunger for food deprivation, thirst for water deprivation, pain, etc.).

The current chapter reviews the evolutionary processes and hereditary mechanisms which resulted in the structure of the human body. We will see how our brain and nervous system transmit and interpret sensory information relaying it to parts of the body capable of responding. All of the inferences and conclusions drawn regarding how our internal processes enable us to adapt to our environment are based upon behavioral observations. At times you may wonder why so much detail is provided regarding human anatomy. You were expecting a course in psychology, not biology. I have done my best to emphasize those parts of the nervous system crucial to our survival and achievements as a species. We will start with a discussion of how human anatomy evolved.

Darwin’s Theory of Natural Selection

Between December of 1831 and October of 1836, Charles Darwin took one of the most important geographic and intellectual journeys in recorded history. On this voyage he collected fossils and observed many forms of wildlife. Upon returning to England and examining his evidence, Darwin detected patterns in variations of animals seemingly related to environmental conditions. For example, he observed that the size and form of a species of birds’ beaks appeared related to the types of available foods (see Figure 2.1). Eventually he published The Origin of Species (1859), arguably the most influential book in the history of biological (if not all) science.

Figure 2.1 Darwin’s finches

Darwin was familiar with the selective breeding practices of farmers designed to result in improved stocks. He reasoned that a similar selective process could occur as the result of natural causes (i.e., natural selection). That is, if environmental factors resulted in some animals having an adaptive advantage relative to others, those animals would be more likely to survive long enough to reproduce. With respect to the birds, those possessing the type of beak best suited to eating the available food type would be able to consume more food and be more likely to survive. Similarly, if some animals possessed a characteristic resulting in their being more attractive to potential mates, they would be more likely to breed (Figure 2.2).

Figure 2.2 Sexual selection

The most controversial aspects of Darwin’s theory of natural selection relate to human evolution. The implication is that our physical structure, and therefore our behavioral potential, is the result of a natural process related to arbitrary environmental factors. Darwin did not at first relate natural selection to human evolution but eventually did so in his later publication, The Descent of Man (1871). It was not until a century later that a substantial number of fossils suggesting very gradual changes in human structure were discovered. This provided physical evidence for human evolution through natural selection.

You might be wondering if the human being is still evolving. In fact, there are several examples of relatively recent adaptive biological modifications apparently resulting from environmental changes. For example, tens of thousands of years ago, humans started moving to higher altitudes. DNA samples from cultures with a history of living in the mountains included genes impacting upon the amount of hemoglobin in the blood (NY Times, May 30, 2013). Individuals with these genes would be better able to cope with the low oxygen levels characteristic of high altitudes. For example, Tibetans tend to have broader arteries and capillaries than nearby Chinese populations living in low-lying areas. These broader vessels permit greater blood flow and a corresponding increase in delivery of oxygen to the cells of the body.

Heredity and Genetics

Darwin did not possess our current knowledge of the mechanisms involved in heredity, the transfer of characteristics from parent to child. He thought that half the characteristics of each parent were combined and transmitted to the next generation. This was a plausible hypothesis given the obvious similarities and differences between parents and offspring. However, if nothing else was involved, natural selection could not occur. Darwin had specified a process for selection but not for the potential variation in genes necessary for change to occur over time. The possibility of genetic mutation was yet to be discovered.

Although occurring at about the time that Darwin published The Origin of the Species (1859), Gregor Mendel’s genetic research with peas did not attain influence until early in the twentieth century. Mendel’s findings enabled Theodor Boveri (1904) to demonstrate the role of chromosomes (tiny threads contained within a cell’s nucleus) in heredity. Cells are the basic building blocks for plants and animals. The human body is comprised of trillions of cells. In 1910, Thomas Hunt Morgan, studying heredity in the fruit fly, demonstrated that genes were located on chromosomes in the cell nucleus. Genes are the basic units of heredity and ordinarily occupy constant positions on chromosomes. Genes are comprised of DNA (deoxyribonucleic acid), which includes all the information required for cell replication. Nearly every cell in the body has the same DNA. In 2003, the Human Genome Project reported that the entire human genome (i.e., all the genetic information characteristic of our species) consisted of approximately 20,000 genes. We now know that most genetic variation results from mutation, a permanent chemical change in the composition of a gene’s DNA. Mutations are rare, and ordinarily provide no adaptive advantage. Thus, it is not surprising that evolution through natural selection is very slow, taking millions of years in humans. First, an adaptive mutation must occur in a member of a species which must be fortunate enough to survive and successfully mate. Then, multiple generations would be required for this difference to show up in a significant number of other surviving individuals. It should be emphasized that the adaptive value of a mutation depends upon the environment in which it occurs (Figure 2.3). For example, one third of the indigenous inhabitants of Sub-Saharan Africa carry the gene for sickle cell disease. This gene increases immunity to malaria, making it adaptive in Africa while being maladaptive elsewhere.

Figure 2.3 Explanation of evolution

Genotypes and Phenotypes

The inherited instructions contained within an individual’s genes are referred to as its genotype. Your DNA includes all the information required to create an individual with your exact physical characteristics, susceptibility to specific diseases, and even some of your temperament. At fertilization, humans inherit 46 chromosomes, 23 apiece from our biological mothers and fathers. The 23rd male chromosome determines the sex of the child. This is because females carry two of the same sex chromosome (called X) whereas males carry one X and one Y (male) chromosome (see Figure 2.4). The chromosome pairs and DNA sequences are structurally similar. Traits are passed on from generation to generation through the DNA contained in genes on these chromosomes.

Figure 2.4 The Y-chromosome

Mendel discovered that when crossing plants with different characteristics (e.g., white or purple) the result was not a blend. Rather, one of the initial characteristics would occur (e.g., the next generation would be purple). Mendel referred to this as a dominant trait and to the other as a recessive trait. For example, in humans brown hair is dominant over red hair. This means that if a child inherits a brown gene from one parent and red gene from the other parent, her/his hair will be brown. However, since that child carries both gene colors, it is possible that offspring will inherit red hair. Traits can skip generations.

The observable physical and behavioral characteristics of a species are referred to as its phenotype. We saw in Chapter 1 that complex human behavior is the result of an interaction between hereditary and environmental variables. It is also true that environmental factors interact with genetic factors with regard to physical traits. For example, an individual’s height and weight can be influenced by nutrition, infection, and other variables.

Human Evolution

It is estimated that the universe is 13.8 billion years old and that the earth is 4.54 billion years old (Dalrymple, 2001). The human being is the most complicated animal on earth. Physical evidence suggests life in the form of simple cells first appeared 3.6 billion years ago. Half a billion years ago, animal life emerged from the sea. Over time, closer approximations to a modern human being appeared. In terms of biology’s family tree, humans are considered primates, a branch including apes, monkeys, and lemurs for which we have discovered fossils dating back approximately 55 million years. The human being’s closest existing primate “relatives”, chimpanzees, bonobos, and gorillas, diverged approximately four to six million years ago. Fossilized evidence suggests the first bipedal animals (i.e., standing on two legs) appeared approximately seven million years ago with the earliest documented evidence for humans (i.e., members of the biological genus “Homo”) dating back approximately 2.3 million years. It is at this time that we observe the first indication of use of stone tools by Homo hablis. This and other transformational events are depicted in Figure 2.5. Note that the brains of early humans were comparable in size to those of chimpanzees and gorillas. This size more than doubled over the course of 2 million years until the appearance of Homo sapiens (modern humans) approximately 200,000 years ago.

Figure 2.5 Human timeline

None of the transformational discoveries listed in Figure 2.5 was inevitable. Evolutionary biologist Jared Diamond (2005) wrote a wonderful Pulitzer prize-winning book tracing the history of the human being leading up to and after the last ice age, approximately 13,000 years ago. He describes how features of the climate and environment impacted on the course of development of humans on the different continents and why some cultures eventually became dominant over others. For most of our time on earth, variations of the human species survived as nomadic small bands of hunter/gatherers in Africa. Diamond (2005, 36-37) describes fossilized evidence that humans migrated to Southeast Asia approximately 1 million years ago, with Homo sapiens reaching Europe ½-million years ago. Existing evidence suggests that modern humans reached the Americas between 14,000 and 35,000 years ago. Diamond (2005, 87) provides an overview of the causal factors impacting upon the human condition. Geographic and climatic conditions affecting the availability of wild plants and animals determined the possibility of development of agriculture and animal domestication. Localized food production enabled establishment of more permanent residences and larger communities. Food storage permitted surpluses, freeing people from survival demands on a day-to-day basis. This resulted in development of new “occupations” and technologies, dramatically altering the human condition.

My students readily admit that where they were born was an extremely important yet arbitrary event impacting upon the course of their life. If they were born and lived in the rain forest they would not be prepared to attend college. Alternately, if at their present age they were dropped in the rain forest without modern technologies or assistance from natives, they would probably not survive.

The terms “human evolution”, “ human condition”, and “human potential”, must be carefully analyzed to be most meaningful. Our potential as individuals and as a species starts with the physical structure (i.e., anatomy) that evolved through the process of natural selection. The Mostly Nature section of this book describes how our anatomy permits us to sense specific sources of physical stimulation originating from outside (Chapter 3) and within (Chapter 4) our bodies. The current chapter describes how the anatomy of our brain and nervous system enables us to process and coordinate this physical stimulation and transmit information to those parts of our body capable of responding. Our anatomy places limits on the types of physical information we are able to sense and the types of responses we are able to make. These limitations meant that we were not always capable of surviving and reproducing under all the geographic and climatic conditions that existed on earth. Our physical structure, however, included the potential to touch, manipulate, and change the planet. The development of tools and technologies magnified this capability, eventually resulting in transformative changes in our environmental conditions. We refer to the interface between our physical structure and environment as the human condition. Over the millennia, humans acquired the capability of surviving anywhere on this planet, traveling to the moon, and exploring the universe. The fascinating story of the past, present, and future potential of our species starts with an understanding of human genetic potential

Human Genetic Potential

When I was a child I faithfully watched the Superman TV show. I would play with my friends, pretending to be Superman, and try to leap off a step while wearing my cape (actually a towel). Despite doing my best to imitate my hero I never took off. I wasn’t a bird or Superman. Flying was beyond my genetic potential. We saw that the human brain significantly increased in size over the course of evolution. A convenient way of considering what constitutes the genetic potential for human behavior is to examine the human motor homunculus (little person). This is a representation of the amount of “brain space” in the cortex allotted to different parts of our body for acting upon our environment (see Figure 2.6). Consistent with the distinctive human DNA described in Figure 1.2, a disproportionate amount of the cortex is allocated to organs related to speech (lips, jaw, tongue, and voice box) and to the hands (particularly the thumb). The ability to manipulate our facial muscles, tongue, and larynx provides the potential to emit an enormous variety of vocalizations. Initial attempts to teach chimps to speak (Hayes and Hayes, 1952) were unsuccessful, primarily due to limitations in the use of these body parts. Our ability to manipulate our fingers and thumbs to form the “precision grip” enables us to grasp and hold objects of different sizes and shapes.

Figure 2.6 The motor homunculus

Millions of years of evolution resulted in an animal with the genetic potential to learn complex behaviors, speak and create tools. This potential took a very long time to emerge. However, once realized, the combination of imagination, communication, and manipulation resulted in humans dominating and changing our planet. Theodosius Dobzhansky (1960), a noted Russian genetic biologist, stated

“Mutation, sexual recombination and natural selection led to the emergence of Homo sapiens. The creatures that preceded him had already developed the rudiments of tool-using, tool making and cultural transmission. But the next evolutionary step was so great as to constitute a difference in kind from those before it. There now appeared an organism whose mastery of technology and of symbolic communication enabled it to create a supraorganic culture. Other organisms adapt to their environments by changing their genes in accordance with the demands of the surroundings. Man and man alone can also adapt by changing his environments to fit his genes. His genes enable him to invent new tools, to alter his opinions, his aims and his conduct, to acquire new knowledge and new wisdom.” The “supraorganic culture” Dobzhansky describes, results from the multiplicative effects of human’s shared imaginings, communications and manipulations. Throughout this book we will seek to understand our potential to transform the world, the human condition and our individual selves. We start with the human genotype.

The Nervous and Endocrine Systems

The Nervous System: Connecting Sensation and Movement

As we consider the human genotype, we will start by providing an overview of the nervous system (see Figure 2.7), those structures which transmit information regarding external and internal stimulation and coordinate behavior.

Figure 2.7 Overview of human nervous system

The central nervous system, consisting of the brain and spinal cord, organizes and interprets information received from the peripheral nervous system and initiates responding. The somatic division of the peripheral nervous system responds to sensory information originating outside the body and stimulates the skin, joints, and skeletal muscles. This type of behavior is often considered voluntary. The autonomic nervous system governs the activity of the smooth muscles and glands internal to the body involved in circulation, respiration, and digestion (see Figure 2.8). This type of activity is often considered involuntary. The sympathetic division results in arousal under stressful or dangerous conditions as the body is prepared for “fight or flight.” The parasympathetic division calms the body upon removal of the stress or danger.

Figure 2.8 The autonomic nervous system

Making the Physical Connections: The Neuron

Even very simple animals require some way of connecting environmental input with behavioral output. Specialized nerve cells called neurons are required to respond to external and internal stimulation (i.e., sensory neurons) and carry information to parts of the body capable of responding (i.e., motor neurons). A third type of cell referred to as an interneuron connects nerve cells to each other. Nervous systems consist of these types of specialized neurons and range in size from a few hundred nerve cells in worms to approximately 100 billion nerve cells in humans. Neurons are capable of transmitting information electrically and chemically. Figure 2.9 portrays the major parts of a neuron. Dendrites are small branches which can connect to nearby neurons. A single axon can extend in length up to about a meter in humans and connect to the dendrites of more distant neurons. For example, a neuron could connect the spinal cord to a foot.

Figure 2.9 The neuron

Nerve cells “fire” (i.e., achieve their electrical action potential) according to an all-or-none principle. That is, either the cell is totally activated or not at all. Increasing the intensity of stimulation does not increase the likelihood of a nerve responding. Rather, it increases the nerve’s rate of firing (i.e., frequency over time). For example, as a lamp becomes brighter, this does not increase the likelihood of a receptor cell in your eye firing. Rather, it increases the frequency with which the receptor cell fires. Nerves can fire at rates as high as a thousand times per second.

Making Chemical Connections: Neurotransmitters

The chemical exchange between neurons occurs at synapses, the small spaces separating the dendrites and axon endings (see Figure 2.10).

Figure 2.10 The synapse

The first nerve cell releases chemical neurotransmitters that can bind with receptors in the second neuron. The exchange can result in excitation or inhibition, depending upon the type of receptor activated. Figure 2.11 lists the major neurotransmitters along with their roles in the body.

Figure 2.11 The major neurotransmitters

Psychoactive drugs can affect mood, thought, and behavior. Most achieve these effects by impacting upon neurotransmitters and synaptic connections. In Chapter 11 (Maladaptive Behavior), we will consider the use of psychoactive drugs in the treatment of depression and schizophrenia.

The Brain

For literal and figurative reasons, it is tempting to refer to the human brain as evolution’s crowning achievement. After all, the brain sits atop our nervous system and enables our most complex overt and covert behaviors. Your thoughts, your feelings, all the complex things you do, would not be possible without this organ housed inside your skull on top of your head.

The human brain is similar in construction to the brains of other mammals but much larger in comparison to the size of our bodies. Without the increase in brain size occurring during human evolution it would not matter if we inherited the physical structures necessary to speak and create tools. This potential would never be realized. Manhattan would still look the same as it did 400 years ago. We are now using our remarkable brain to study itself. The United States government declared the 1990s as the “Decade of the Brain” and much progress has been made in understanding how the brain operates. President Barack Obama of the United States declared “The BRAIN (Brain Research through Advancing Innovative Neurotechnologies) Initiative” in 2013, hoping to advance this knowledge.

There are many ways of describing the brain in terms of its structure (i.e., anatomy) or function (i.e., parts operating together in producing a specific effect). Figure 2.12 shows the major parts of the human brain. The prefrontal cortex is involved in the higher human cognitive functions including attention, perception, thinking, memory, language and consciousness.

Figure 2.12 Human brain

The brain is an adaptive organ connecting sensation with movement. Besides the primary somatosensory area in the parietal lobe, sensory areas include the occipital lobe for vision and temporal lobe for hearing. Besides the primary motor area at the rear of the frontal lobe, motor areas include the brain stem and spinal cord. The rest of the cortex is referred to as association areas and is dedicated to perception and cognition. It is the size and structure of this area which expanded enormously as humans evolved and enabled us to not only survive but to transform the human condition.

A human brain weighs about three pounds and feels “squishy” (something like gelatin). The cerebral cortex covers most of the brain and is comprised of nerve fibers folded in such a manner (called convolutions) to increase the amount of surface area in the total space. There are two symmetrical halves often referred to as the left brain (or hemisphere) and right brain (or hemisphere). The two halves are connected by the corpus callosum, a thick network of nerve fibers enabling the two sides to communicate. The left side of the brain connects to the right side of the body and vice versa. Certain activities appear more characteristic of one side than the other (see Figure 2.13). These distinctions are referred to as lateralization. Despite the different emphases, both sides usually act in concert in carrying out these activities (Toga & Thompson, 2003).

Figure 2.13 Brain lateralization

Most of the expansion in the size of the human brain occurred in the frontal lobe. This part of the brain is involved in self-control, described in Chapter 1, and in abstract thought and problem-solving, described in Chapter 7. The small occipital lobe is dedicated to vision, described in Chapter 3. At the borders of the frontal and parietal lobes is a deep fissure (the central sulcus) where large strips of neural tissue dedicated to sensation (the primary somatosensory cortex) and movement (the primary motor cortex) meet. The temporal lobe is primarily involved with memory and language, described in Chapter 6. The parietal lobe is involved with sensation originating in the skin, muscles, and joints.

The Endocrine System: Hormonal Regulation

The endocrine system consists of ductless glands that secrete hormones (chemical messengers) into the blood stream to maintain homeostasis. It exists in all animals having a nervous system. Like the nervous system, the endocrine system enables communication between different parts of the body.

The endocrine system maintains homeostasis through a series of feedback loops, the most important of which are controlled by the hypothalamus interacting with the pituitary gland. Often, the hypothalamus stimulates the pituitary gland to secrete an activating hormone to another gland. If a signal is transmitted to a gland, indicating low blood levels of its hormone, it secretes additional amounts into the blood stream. Once the optimal level is restored, the gland stops secreting the hormone. In this way the endocrine system plays its critical role in metabolism, growth, sexual development, reproduction, and responding to stress. Figure 2.14 shows the locations of the major glands.

Figure 2.14 Major gland locations

The pituitary gland connects to the base of the hypothalamus and is often referred to as the master gland since it secretes several different hormones impacting upon other glands involved in maintaining homeostasis. Hormones secreted by the pituitary control growth, blood pressure, water balance, temperature regulation, and pain relief. The pineal gland is located at the base of the cortex between the two hemispheres and next to the thalamus. It influences the sleep-wake cycle by secreting the hormone melatonin when stimulated by light. The thyroid gland is located in the neck by the larynx (voice box) and affects metabolism by controlling the rate at which energy is expended. It is one of the glands under the control of the pituitary which secretes thyroid-stimulating hormone (TSH). The pituitary in turn is controlled by the hypothalamus through the release of thyrotropin-releasing hormone (TRH). Humans usually have four parathyroid glands located on the rear surface of the thyroid gland. These control the amount of calcium in the blood and bones. The thymus is located below the thyroid gland in the middle of the chest. It is an important part of the immune system. Damage, such as through contracting the HIV virus, can result in increased susceptibility to infection (e.g., AIDS). The spleen lies toward the bottom of your rib cage and is involved in the removal of red blood cells. The adrenal glands are located on top of the kidneys and through the release of epinephrine (adrenalin) are significantly involved in the body’s “fight-or-flight” response in reaction to danger. The sex glands (ovaries for the female and testes for the male) secrete hormones controlling the development of the reproductive sex organs and secondary sex characteristics (e.g., pubic hair) during puberty.

Self-Control and Biological Psychology

Life is a rat race

In the first chapter, we saw how an experiment conducted with pigeons provided important insights into the self-control process. At the end of each chapter, I will consider implications of the material to achieving your own potential. You might be wondering how this could be possible in a chapter describing human biology. Think of the implications of neuroplasticity. By making environmental manipulations, you can actually “rewire” your brain. What may surprise you is that studies measuring EEGs and MRIs with humans have demonstrated that physical activity affects the brain. It is known that the cortex and hippocampus atrophy in the aged. Experimental studies with other animals (primarily rats and mice) have demonstrated that exercise can actually increase the number of nerve cells in the hippocampus (Brown, Cooper-Kuhn, Kempermann, van Praag, Gage, & Kuhn, 2003; van Praag, H., Shubert, Zhao, & Gage, 2005; Eadie, Redilla, & Christie, 2005).

You are probably aware of the many benefits of exercise. The Public Health Service concluded exercise was one of the most significant ways in which humans could improve their health (Powell, & Paffenbarger, 1985). Consistent aerobic exercise has been found to reduce the likelihood of developing hypertension (high blood pressure), heart disease, type II diabetes, and osteoporosis (thinning of the bones). A good way to understand research is to use the scientific schema I described in Chapter 1. Ask yourself to describe out loud or in writing the question being investigated, the procedures used to investigate the question, the research findings, and the conclusions. It is often helpful to try to imagine yourself as a research subject. I am sure it is easy for you to imagine being on a treadmill or exercise bike with electrodes attached to your head to take EEG readings. That would enable us to observe the effects of independent variables (e.g., duration of exercising, speed, the incline on a treadmill or resistance on a bike) on a dependent variable (e.g., changes in EEG recordings).

In order to obtain more precise data regarding the effects of exercise on the brain, it is necessary to examine the brain itself rather than simply recording EEG or obtaining MRI scans. This type of invasive research can only be conducted on other animals. You may be wondering, how is it possible to study the effects of exercise on rats and mice. Are there rat and mice gyms or health clubs? Do they have swimming pools, bikes, and treadmills? The answer is, sort of (Figure 2.15).

Figure 2.15 Rat in a running wheel.

One study compared the effects of moderate and more intense exercise on two types of learning and on changes in the presence of neural plasticity-related proteins in the hippocampus and amygdala (Liu, Chen, Wul, Kuol, Yu, Huang, Wu, Chuang, & Jen, 2009). Both groups were taught to swim to the end of a water maze and to avoid shock in another apparatus. Then, one group of mice engaged in self-paced wheel running for four weeks and another group received more intense workouts on a treadmill. Both groups were then retested on the two tasks and underwent surgery to assess changes in their brain chemistry. After their four weeks of exercise, both groups improved their performance in the water maze. Only the group given the more intense treadmill workouts improved on the more difficult shock avoidance task. It was determined that this group increased the levels of specific proteins in both the hippocampus and amygdala whereas the self-paced group only experienced increases in the hippocampus. The authors concluded that different exercise routines can differentially affect learning and brain chemistry.

In Chapter 1, I listed examples of the behaviors my students have targeted in self-control projects. Many students are interested in improving their cardiovascular fitness by engaging in aerobic exercises (i.e., involving sustained rhythmic activity). According to the American College of Sports Medicine (ACSM) Physical Activity Guidelines for Americans (Garber, 2011), one should engage in 1-1/4 hours (75 minutes) of intense (e.g., jogging or running) or 2-1/2 hours (150 minutes) of moderate (e.g., brisk walking) exercise per week. You can break up the activity into sessions lasting at least 10 minutes. For example, you could walk briskly for half an hour on five different days, or 50 minutes on three different days, etc.

Usually, for exercise projects, students assess the frequency, duration, and intensity of exercises they would like to perform. In Chapter 5, we will discuss application of learning principles to modify behavior. However, if you would like to try a self-control intervention before then, you could implement an adjusting criterion procedure. In the case of aerobic exercise, start by obtaining baseline data on the frequency, duration, and (when applicable), the intensity of your sessions. If you do not exercise at all, try a minimal amount (e.g., five or ten minutes) on three different days. Once you have stable baseline data, you will be ready to adjust the criterion upward in order to earn a reward. For example, you could require a ten per cent increase (to five and a half or eleven minutes). If you earn the reward three sessions in a row you can increase the criterion by an additional ten per cent, and so on until you reach your ultimate objective. The reward could be something tangible such as a treat (but watch out for the calories!) or money, or an enjoyable activity such as reading, listening to music, playing video games, engaging in social networking, etc. Make sure you leave sufficient time to study for your courses, though. Otherwise you will need to implement an adjusting criterion procedure on study time!

Introduction to the Science of Psychology

Assumptions

There are things I think I know, things I think I might know, and things I know I don’t know. I have learned that it is important to be able to tell the difference. In this book, I am trying to share some of the most important things I think I know about psychology. What I mean by important is that I think you will find many of these things interesting and some helpful in contemplating human potential and living your life under your unique human conditions.

I don’t know you personally but I am going to try to communicate based on certain assumptions. My assumptions are usually inferences based on things I think I know. I think I know that you just completed reading this sentence. Another thing I think I know (but am not as certain of), is that you are a student or someone interested in psychology. Accordingly, I will try to relate the material to college’s and life’s usual demands (e.g., passing objective and essay examinations; time management, problem-solving, health and weight control, etc.).

Mighty oaks from tiny acorns grow.

In their attempt to understand their world and the meaning of their existence, humans increasingly rely on the scientific method to understand nature. All sciences are interested in establishing cause and effect relationships that apply under natural conditions. Over the past 400 years, there have been enormous advances in the physical, chemical, and biological sciences. This has resulted in applied technologies that have transformed the planet and the human condition.

This book describes the results of application of the scientific method to understanding the behavior of individual animals including humans. As a science, psychology studies how genetics (i.e. heredity or nature) and the environment (i.e. experience or nurture) influence covert (i.e. thinking and feeling) and overt behavior. That is, psychology assumes that the same principles that apply to acorns and oaks apply to human beings. Exposure to sunlight, water, and fertilizer determine the development of acorns. Throughout subsequent chapters we will see how different environmental variables influence human development. Traditionally, psychology has been broken down and introductory textbooks organized according to distinct content areas. In this book, these content areas are separated into those heavily influenced by genetics (biological psychology, sensation, motivation); those heavily influenced by experience (learning and cognition); and those emphasizing nature/nurture interactions (lifespan development, personality, social psychology, and maladaptive behavior). As will be observed as you advance through these content areas, the scientific method has been successfully applied to complex and important behavioral phenomena. Just as with other sciences, the establishment of cause and effect relationships has enabled the development of applied strategies.

The idea of potential is a paradox. It implies absolute limits and enormous possibilities. It is simultaneously pessimistic and optimistic. Potential can result in good or harm, creation or destruction. To consider psychology the science of human potential requires recognizing and accepting these contradictions. Every acorn has the potential to become a mighty oak but not every acorn will achieve that potential. Every healthy human child has enormous potential but not every child will achieve their potential.

The first paragraph of the serenity prayer, usually attributed to Reinhold Niebuhr, states:

God grant me the serenity
To accept the things I cannot change;
Courage to change the things I can;
And wisdom to know the difference.

The college experience can be described as encouraging students to consider the meaning of their lives within the context of lives that have been lived and lives that could be lived. This requires knowledge of history and culture to inform one regarding the likelihood of accomplishing change and imagination to consider other possibilities. The hope is that such knowledge and imagination will be applied wisely throughout one’s life.

An amusing distinction related to the serenity prayer describes three types of individuals: those that make it happen (i.e. demonstrate courage), those that watch it happen (i.e. are passive), and those that ask “what happened” (i.e. are clueless). The messages conveyed by the serenity prayer and this distinction relate to human potential. Those that are informed and active in considering options and making decisions are more likely to achieve their potential than those less informed or passive.

The Importance of Grades and Performance Standards

Do you think people have traits? Do you think some students are industrious and others are lazy? We will discuss such issues in Chapter 9 (Personality). I think I know that if you are a student, you care about the grades you receive on exams. It is very difficult to be accepted into a university if you did not do reasonably well on exams. It is unlikely that you would have done well on exams if you didn’t care how you performed. Similarly, you will not excel at anything in life unless you are motivated to meet acceptable standards of performance. Parents and teachers probably tried hard when you were young to get you to care about how you performed in and out of school. We know that with respect to school grades, this often happens early. The reason we know is that research has demonstrated that some Head Start (Edlund, 1972), first-grade, and second-grade students (Clingman & Fowler, 1976) do better on IQ tests if they are given extrinsic rewards (e.g., candy or trinkets) for correct answers . Other students perform to the best of their ability without the extrinsic rewards. We will discuss such issues in Chapter 4 (Motivation & Emotion). Getting students to care about how they performed was obviously very important. Do you think research conducted with rats and pigeons can help us develop procedures to get children to care about their performance in school and on other tasks? We will review related questions later in this chapter and examine some of the practical implications of animal research in Chapter 5 (Direct Learning).

Edlund, and Clingman and Fowler are the first researchers cited in this book. Many more will follow. Complete references are listed alphabetically at the end of the book. You are encouraged to consult the original references whenever you have questions concerning a particular finding or conclusion or wish to obtain additional information. We live in a world where we are continually exposed to information designed to influence our beliefs and opinions. One of the most important skills you can acquire as a student or in life is the ability to determine what constitutes a credible basis for believing something is true.

The Importance of Knowing When You Know and When You Don’t Know

Even experienced students and adults sometimes have difficulty determining when they understand something and when additional (or more likely, different) preparation is required. One of the ways in which I will try to help you determine whether you understand material is by inserting essay questions at the end of major sections. Some of these questions can be answered through memorization. Others will require a level of understanding beyond memorization. They will require integrating key concepts and applying them so that you will appreciate the basis for our current understanding of psychological issues. Test yourself by writing out your answers to these questions. I suspect you will sometimes find that even though you thought you understood the material after you read it, you have difficulty providing a clear, complete, and accurate answer. If this is the case, you will know that it is necessary to review the material until you are able to provide such an answer. For example, can you answer the following question?

The Structure of College and Types of Knowing

Psychology is an academic discipline (i.e., body of knowledge based upon accepted, standardized methods). Before we consider the structure of the psychology curriculum and how it relates to the organization and content of this book, we will consider where psychology fits within the usual college curriculum. College students are asked (sometimes required) to take courses in many academic disciplines. Many of these courses are taught by departments housed in administrative units known as Arts and Sciences. Psychology is almost always housed within colleges of Arts and Sciences encompassing many disciplines not designed to prepare students for specific career paths (e.g., Art & Music, History, Philosophy, Physics, etc.). This is in contrast to pre-professional academic units such as Education, Business, and Nursing.

The psychology major prepares students for graduate education and psychology related vocations such as clinical, counseling, school, and industrial psychology. The American Psychological Association website includes a substantial amount of information concerning career opportunities in psychology (http://www.apa.org/careers/resources/guides/careers.aspx). Another very helpful psychology career website is: www.drkit.org/psychology.According to the Bureau of Labor Statistics the job growth for psychology till 2026 is projected to be faster than the average for other occupations.

Over the years, many students have asked me why they have to spend so much of their first two years taking courses in Arts and Sciences (often referred to as core courses). They indicate the desire to just take courses in their favorite department (often referred to as a major). I often respond to such questions by referring to the famous picture based on the poem, The Blind Men and the Elephant (Saxe, 1872).

Figure 1.1 Blind men and an elephant

Often students are asked to take courses in the arts (e.g., history, literature, art or music, philosophy), “natural” (i.e., perhaps more accurately referred to as “laboratory”), and social and behavioral sciences. Psychology, which may be defined as the scientific study of individual thought, feeling, and behavior, is usually included in the last category with disciplines such as Sociology and Political Science. It is usually not included in the next-to-last category with disciplines such as Biology, Chemistry, and Physics even though, as we shall see, much of its research is conducted in laboratories. The arts, natural sciences, and behavioral sciences may be considered blind men with the elephant representing the human condition. Each perspective is attempting to help you place your life within a broader context of time, place, and ideas. History attempts to base its understanding on artifacts obtained over different time periods. Literature attempts to capture the essence of the human condition in different types of creative narratives (e.g., novels, plays, poems). Art and music provide different types of examples of human creativity. Philosophy applies reason and logic to questions regarding the meaning of life. Sometimes students believe since they have already taken similar courses in high school they will be repeating the same material. We have long known from the cognition literature (see Chapter 7) that repetition improves memory (Ebbinghaus, 1885). Also, you will probably find that your college professors ask you to do more and provide more difficult assignments, even when treating the same material.

Early History of Psychology

Wilhelm Wundt is given credit for founding the discipline of psychology at the German University of Leipzig in 1879. It is there and then that the first laboratory exclusively dedicated to psychological phenomena was established. Prior to then, research that would be considered psychological in nature was conducted in physics and neurology laboratories. Examples would include Fechner’s (1860) psychophysics research investigating just noticeable differences on sensory dimensions and Helmholtz’s studies of vision conducted in the 1850s and 1860s (translated into English in 1924).

Figure 1.2 Wilhelm Wundt

Wundt (1873, 1896) defined psychology as the scientific study of conscious experience or, as some prefer, the study of the mind. His thinking was influenced by the chemist Dmitri Mendeleev, who formulated the periodic chart of elements. Wundt felt the goal of psychology should be to determine the fundamental elements of conscious experience, a sort of “mental chemistry.” His research suggested that the basic elements were images, sensations, and affective states (i.e., emotions) and that these had the attributes of quality, intensity, and duration. Wundt relied upon introspection (i.e., looking inward) as the exclusive methodology. He felt that, with extensive training, individuals could be taught to make objective judgments regarding the attributes of what they were covertly (i.e., privately) experiencing. Thus, a subject might be placed in front of a desk and asked to describe the intensity and duration of her/his images, sensations, and emotional experiences.

Inevitably, other scientists interested in psychology reacted to different aspects of Wundt’s original approach to the discipline. In 1890, Harvard’s William James published his classic textbook The Principles of Psychology introducing much of the content and organization of subsequent introductory psychology textbooks. Edward Titchner, a student of Wundt’s who established a laboratory at Cornell University, made distinctions between Wundt’s and James’ approaches to psychology, labeling the former as structuralism and the latter as functionalism (1898, 1899). The University of Chicago’s James Angell responded (1903, 1907) with the functionalist perspective on the same distinction. This perspective was influenced by Charles Darwin’s (1859) contributions regarding natural selection. Titchner and Angell argued that Wundt’s original goal of analyzing conscious experience did not adequately emphasize the adaptive role played by the mind in survival. The major functionalists, in addition to William James and James Angell, included John Dewey and Harvey Carr of the University of Chicago. In addition to arguing for broadening the goals of psychology, they proposed expanding the methodology beyond introspection to include active experimentation in which the effects of different variables could be investigated.

Figure 1.3 William James

In 1910, Max Wertheimer, a doctorate in psychology, was studying the perceptual experience of apparent movement later labeled as the phi phenomenon. He had purchased a toy stroboscope that subjectively produced the impression of continuity from appropriately timed presentations of still photos (similar to projection of filmed still images in a movie theater) and was searching for subjects to investigate the effect. A friend provided laboratory facilities at the Frankfurt Psychological Institute and introduced him to Kurt Koffka and Wolfgang Kohler, two outstanding post-doctoral students to serve as subject colleagues (Kendler, 1987). This union resulted in the formation of the distinct psychological perspective called Gestalt psychology (Kohler, 1929). The German word gestalt is usually translated as “organized whole” and the catchphrase “the whole is greater than the sum of its parts” succinctly summarizes the major message of this approach. Gestalt psychologists disagreed with structuralism’s goal of analyzing conscious experience. The phi phenomenon was used to exemplify this message. Analyzing the phenomenon into distinct presentations of single photos was inappropriate. They argued that to do so, misrepresented and actually destroyed the very essence of what we perceive. When describing conscious experience, one had to work at the level of complete organized units. For example, to describe a desk in terms of the visual and tactile sensations it produces, does not capture the meaningful whole we perceive.

Figure 1.4 Max Wertheimer

It has been quipped that sciences advance when one scientist stands on the shoulders of another and psychology advances when one psychologist stomps on the head of another. The originator of this comment could have had John Watson in mind. Watson was trained as a functionalist at the University of Chicago and upon graduation accepted an excellent position at Johns Hopkins, where he remained for 12 years. Publication of his Psychological Review article, “Psychology as the Behaviorist Views It” (1913), resulted in no less than a permanent transformation of the discipline. Unlike the functionalists and Gestalt psychologists, Watson considered Wundt’s approach to have been a false start. His manifesto called for a change in the definition, goals, and methods of psychology. Watson reasoned that if psychology were to be considered a natural science the subject matter had to meet the three criteria of being observable, testable, and replicable. Since conscious experience cannot be independently verified by any means, testable questions could not be formulated and results could not be replicated. Watson limited the subject matter of psychology to observable behavior and defined the discipline as the science of individual behavior. The scientific method would be applied to the goal of prediction and control of observable behavior.

Watson’s behaviorism was particularly critical of introspection as a method of inquiry. Not only was introspection inherently subjective, making independently verifiable replication of results impossible, it was a reactive procedure that unnecessarily limited the discipline’s subject matter. A reactive procedure is one in which the observational procedure affects the results. Watson argued that the act of introspecting necessarily altered one’s conscious experience. That is, the research findings obtained while introspecting would only apply under circumstances where an individual is engaged in introspection. This is not ordinarily the case. Also, since only reliable verbal human beings could accurately describe their introspections, it was impossible to study abnormal populations, children, or other animals as subjects.

Figure 1.5 John Watson

Psychology Today

Each of the major early schools contributed significantly to the way psychology is currently practiced. Working backward, it is recognized that our scientific observations are limited to observable behavior (Skinner, 1990). Indeed, just as in other sciences, psychology’s subject matter is expanded with the development of new instruments. Astronomy benefited from the invention of the telescope, biology from the microscope, and psychology from such innovations as the IQ test, personality tests, reaction timer, galvanic skin response (GSR), Skinner-box, electroencephalograph (EEG), magnetic resonance imaging (MRI), computerized recording of behavior, and so on.

Current psychology has profited from the wisdom of the Gestalt psychologists as well. Indeed, a hard lesson was learned when it was realized that many conclusions reached regarding human memory based on the study of nonsense syllables (e.g., GUX) did not apply to meaningful words and sentences. For example, it has been demonstrated that the individual letters in words are processed simultaneously rather than sequentially (Adelman, Marquis, and Sabatos-DeVito, 2010). This means the word is processed as a “Gestalt’ (organized whole), not separate letters.

Functionalism continues to be influential within psychology. Indeed, evolutionary psychology, an approach consistent with major themes of this book, has emerged recently as a unifying perspective for such distinct content areas as biological psychology, learning, and social psychology (Confer, Easton, Fleischman, Goetz, Lewis, and Buss, 2010).

By virtue of being first, Wilhelm Wundt was able to define, state the goals, and develop the methodology of psychology. We have seen that this advantage had its cost since it provided others the opportunity to make suggestions and offer criticisms, not always in a collegial manner. Still, the most important components of structuralism have been incorporated within current practice. The fact that Introduction to Psychology textbooks practically all include chapters on perception, learning, and cognition demonstrates continued interest in conscious experience. We do not directly observe people perceive, learn and think. These topics must be studied in an inferential manner based upon behavioral observations. That is, people behave as though they perceive, learn, and think.

Introspection continues as a methodology for acquiring data in the form of self-report with the inherent limitations of such data being recognized and studied in their own right. Wherever possible, confirmatory measures other than self-report are frequently obtained. For example, in studies designed to reduce cigarette smoking, subjects are often required to provide carbon dioxide measures in addition to cigarette per day self-reports.

Research Methods in Psychology

Scientific Explanation

As mentioned previously, by explanation we usually mean a statement of cause and effect. Scientists refer to potential causes as independent variables and the related effects as dependent variables. Different sciences are defined by the dependent variables of interest. That is, physics studies the effects of different independent variables on matter and energy. Biology studies the effects of different independent variables on life processes. Psychology studies the effect of different independent variables on the behavior of individual animals.

All sciences assume that nature is lawful and that if you study nature systematically the underlying laws can become known. This assumption is referred to as determinism and is not today considered controversial with respect to physics, chemistry, and biology. We look to these disciplines to provide answers regarding questions regarding how nature works and benefit from technological advances resulting from scientific understanding. The assumption of determinism with regard to human behavior, however, is considered very controversial by those believing we possess freedom of the will. I hope to reduce or eliminate the controversy by pointing out that the logical opposite of determinism is not freedom of the will, but non-determinism. That is, the logical opposite of the assumption that nature is lawful is that nature is not lawful. Everyone, including those believing strongly in freedom of the will, acts as though behavior is lawful. We (usually) stop at red lights and proceed when they turn green. We (usually) take turns listening and speaking. We (usually) show up for class on time, etc., etc. None of this would be true if we did not expect others to act in a predictable manner. Predictability, implying lawfulness, can only be true within a deterministic system.

Let us now consider what psychology considers a lawful explanation of human behavior. We start with a couple of scenarios. Imagine that you are in a classroom and a person your age enters, walks over to a wall and starts banging their head against it. Then the person takes a seat and starts talking out loud to someone else, although no one else is present. Someone from the university counseling center enters the room and concludes these behaviors occur as the result of schizophrenia. Another person your age enters the classroom, congested and coughing. Someone from the university health services concludes the person is experiencing these symptoms as the result of influenza.

These two scenarios appear very similar. An individual’s behaviors or physical symptoms are explained by reference to an underlying condition or illness. However, the first example constitutes an example of a pseudo- (i.e., false) explanation whereas the second example could fulfill the requirements of an adequate explanation. Why is that? Both explanations involve terms that are difficult to pronounce and spell. What makes influenza “better” than schizophrenia? Remember, by explanation we mean a statement of cause and effect. This requires a separate observable potential cause (independent variable) and effect (dependent variable). In the case of influenza, a specific bacteria or virus can be detected through the appropriate tests. The term influenza does not simply stand for a syndrome of symptoms. It stands for the relationship between a specific “germ” and a specific syndrome. It is possible to test and replicate the relationship between this specific germ and specific symptoms. This is not the case with the term schizophrenia which is defined exclusively on the effect (dependent variable) side (DSM 5, 2013). It is circular to explain a phenomenon with the name for the phenomenon. Why does the person behave that way; because the person is schizophrenic. How do you know the person is schizophrenic; because the person behaves that way.

As will be shown repeatedly, pseudo-explanations can be extremely problematic in psychology. For example, it is known that students’ getting out of their seats can be increased through the attention of their teacher (Allen and Harris, 1966). If you were informed that your child gets out of the seat frequently because of attention deficit hyperactivity disorder (ADHD), you might not search for an alternate explanation. Even worse, there is the potential for the development of a self-fulfilling prophecy. That is, by virtue of being labeled ADHD, others might treat your child differently, resulting in the problem behaviors increasing in frequency. Earlier, I emphasized the importance of knowing when you know something and when you do not. The possibility of accepting a pseudo-explanation is an important example. One of the most valuable lessons you can learn is when you understand a phenomenon (in psychology or otherwise) and when you do not. Be vigilant for pseudo-explanations. Always look for testable relationships between observable independent and dependent variables.

Nature/Nurture and Explanation

Many psychologists and psychiatrists are searching for the cause(s) of schizophrenia. Where do they look? Based on the influenza example, one might consider the possibility of a genetic influence or a germ. Psychologists look to nature (heredity) and nurture (the environment) for causes. The assumption is that our genes determine our total potential for development which is then realized through exposure to appropriate environmental events. An example with plants was provided by a high school valedictorian who thanked his parents, friends, and teachers for helping him prepare for life. He thanked his parents for providing water, his friends for their sunshine, and his teachers for producing so much fertilizer!

I am sure you are familiar with so-called nature-nurture controversies. For example, some suggest that heredity is more important than the environment or vice versa with respect to schizophrenia or intelligence. In technical journals, one will see reference to heritability ratios as indications of the extent to which behavior results from genetic influences. This is another controversy that I believe is best reframed, as we did with questions regarding freedom of the will. Let us combine some of the elements of the novels Jurassic Park (Crichton, 1990) and Tarzan of the Apes (Burroughs, 1914) to show how. Someone is exploring the sight where Marie Curie or Albert Einstein died and discovers a mosquito frozen in amber. It is determined that this mosquito stung the scientist while alive and it is possible to extract the DNA and clone it. A healthy, lively infant results and is given to a loving pair of gorillas to raise. Obviously, this infant’s genetic potential will never be realized in this impoverished environment (by current technologically advanced human standards). The reverse is also true. We could provide a wonderful, loving pair of human parents with a chimpanzee to raise. This, in fact, was done with the famous chimp Washoe, the hero of a wonderful book, Next of Kin (Fouts, 1997). I can guarantee you that this book will make you laugh and make you cry and that you will never think of chimpanzees in the same way. Chimpanzees share more than 98% of their DNA with humans (Pollard, 2009). Still, by human standards, Washoe does not attain many of the complex abilities that the great majority of us do as adults. That remaining 2% of DNA accounts for some very significant differences in our genetic potential.

Nature/nurture issues frequently arise in psychology. For example, to what extent is intelligence (see Chapter 7), personality (see Chapter 9), or abnormal behavior (see Chapter 11) influenced by each? Psychology studies the influences of genetics (nature) and experience (nurture) on every aspect of individual behavior. In the next section, the methods developed by psychologists to scientifically study the effects of different variables on behavior will be described.

The Scientific Revolution

It has been suggested that the most significant accomplishment of the previous millennium was the transition from relying upon personal experience or authority figures to relying upon empirical testing to understand nature (Powers, 1999). Thus legend has it that Galileo climbed to the top of the leaning tower of Pisa to drop rocks in pairs to determine the effect of the weight of objects on how quickly they fall. Familiar experiences with very light objects (e.g., paper or feathers, which are disproportionately influenced by air currents) could lead us to believe that heavier objects fall faster than light objects. Even today, most people believe this is true. However, simple tests, such as by simultaneously dropping a dime and quarter, lead to the correct conclusion reached by Galileo that the weight does not matter. This reality is confirmed when studies are conducted in vacuums eliminating atmospheric effects.

It is not coincidental that reliance upon empirical testing resulted in tremendous strides in physics, chemistry, and biology. Many of the technological advances we take for granted in our modern world (e.g., electricity, plastics, and inoculations against diseases) subsequently emerged. Figure 1.6 dramatically shows the transformation of New York City that took place over the course of the four centuries since Henry Hudson arrived there in 1609. The island was transformed from the forest it had been for hundreds of thousands of years to a modern metropolis. These spectacular feats of engineering and construction would never have been possible without the systematic application of the scientific method. The combination of science and practice has enabled us to develop powerful technologies capable of transforming our environment and way of life. Clearly, we must appreciate this powerful methodology if we are to understand our contemporary human condition.

Figure 1.6 How Manhattan Island appeared in 1609 when Henry Hudson landed there and in 2009

Scientific Questions

Not everything that can be counted counts, and not everything that counts can be counted

(Cameron, 1963)

Might a contemporary scientist be interested in determining the number of angels that could fit on the head of a pin? When I ask this question, students frequently chuckle, some seeming uncomfortable. When I ask, might a contemporary scientist be interested in determining the number of influenza viruses that could fit on the head of a pin, students usually respond “yes”, immediately recognizing the difference between the questions. Given the limitations of human senses and currently existing technologies, we are unable to observe the presence of angels and therefore to count them. However, thanks to the existence of electron microscopes we could theoretically count influenza viruses. The fact that electron microscopes did not exist until 1931 does not mean that influenza viruses did not exist or that they were not important. The scientific method is limited to questions that may be tested through empirical observation. Only then is there the possibility for replication of results, a requirement for scientific advancement. However, if the limitations of being observable, testable, and replicable are met, we know of no more reliable, powerful strategy for determining cause and effect in nature. Next, we will review the early history of psychology, considering the implications and challenges of applying the scientific method to the subject matter.

Internal and External Validity

There are two assumptions underlying the title of this book, Psychology: The Science of Human Potential. The first is that application of the scientific method has enabled us to develop reliable cause and effect relationships between specific hereditary and experiential independent variables and specific behaviors. The second assumption is that these principles apply to our potential as individuals and a species. The first of these assumptions relates to the research issue known as internal validity and the second to the issue known as external validity. Internal validity is the ability to draw cause-effect conclusions from research findings. External validity is the ability to apply cause-effect conclusions under naturalistic conditions.

It is almost universal on college campuses that the laboratory sciences occupy separate facilities from the humanities. Laboratories create isolation from many of the extraneous variables that might influence research results. They typically include extensive electrical and plumbing requirements beyond those of “chalk-and talk” classrooms. It is the emphasis upon control and precision that results in the laboratory sciences being described as “hard” in comparison to non-empirical disciplines. For example, if one were interested in replicating Galileo’s observations regarding the influence of the effect of weight on the rate at which an object falls, it is advantageous to perform the observations inside where the wind would not play a role. Laboratories also permit greater control of the independent variable and precision in the measurement of the dependent variable. Today we could create perfect spheres that differ only in weight and measure the time taken to fall any distance in millionths of a second. Despite the differences between the laboratory and external environments, we would expect the findings to continue to apply. In fact, this would constitute an empirical question that could be tested using the scientific method. Any time the findings did not apply would suggest further research to determine the cause(s). For example, fans of different sizes and power could be placed at different locations to systematically study wind effects.

Non-experimental Research Methods

Experimentation, where the researcher is able to manipulate the independent variable and control for the influence of other possible confounding variables (i.e., other potential influences on the dependent variable), is the most reliable and powerful method for determining cause and effect. However, it is not always possible to conduct experiments in psychology (or other sciences, for that matter). Sometimes, you do not have the ability to manipulate a variable. For example, one cannot “make” someone male or female, or a particular age, etc. We can only select subjects already possessing the different attributes. We do not have the power to manipulate geographic or climatic variables to see the extent to which they influence behavior. Many variables cannot be manipulated for ethical reasons. For example, we cannot systematically punish children severely to see if that is an effective technique for eliminating undesirable behavior. Indeed, some have even questioned studying the effect of punishment on the dangerously self-destructive acts of autistic children (Bettelheim, 1985). For these reasons, many in the other laboratory sciences describe psychology as “soft.” Sometimes they even question the possibility of conducting psychology as a science. The research findings described in this book attest to the fruitfulness of applying the scientific method to psychological questions. The discipline of psychology frequently applies non-experimental designs under conditions where experimental procedures are logistically impossible, prohibitive in cost, or unethical.

Frequently non-experimental studies can provide information about the relationship between variables despite not being able to demonstrate cause and effect. However, even when relationships between variables are compelling, for example when a substantial statistical correlation exists, it is still not possible to conclude cause and effect. Often there is a hidden third variable underlying the correlation. For example, it is likely there is a high correlation between the number of books in one’s home and success in school. That does not mean that by simply providing books to an individual it will improve school performance. It is likely the number of books in one’s home is indicative of a number of economic and attitudinal advantages. Still, the fact that this correlation exists is informative and could lead to an experiment to test whether there is a cause and effect relationship between the number of books and school performance.

Experimental Research Methods

Experimental procedures involve the systematic manipulation of an independent variable in such a way as to permit the demonstration of an effect on a dependent variable. Theoretically, in psychology this would involve manipulation of genetic and/or experiential independent variables to see the extent to which they influence individual behavior. In practice, due to current technological limitations with respect to “genetic engineering”, experimental psychological research practically always involves manipulation of experiential variables. Following up on the previous example, the number of books in a home would need to be systematically manipulated as described below.

Studies Comparing Groups

In psychology, group studies conforming to major statistical designs (e.g., t-tests, analysis of variance, etc.) are the most popular experimental procedures. Small-N (i.e., small number of subjects) designs are also popular and have their distinct advantages. Before describing them, we will review the rationale underlying group studies. As mentioned before, even animals of the same species (especially humans) differ from each other. The logic of group studies is that with sufficient sample sizes (i.e., the number of subjects in each group), random assignment to conditions (groups) should result in comparable averages for all subject characteristics. That is, if 200 children were randomly selected from the general school population and assigned to two conditions according to the flip of a coin, we would expect each condition to start out with approximately the same gender, racial, and ethnic composition, to be of the same average height, age, intelligence, etc. Therefore, if after manipulation of the independent variable (e.g., the number of books provided) the groups differed significantly in their academic performance, it would be possible to conclude that the number of books caused the difference rather than a subject characteristic.

The great majority of experimental research studies cited in this book are group designs. Often it is only necessary to include two groups to demonstrate an effect, one usually receiving a type of experience (often referred to as the experimental group) and the other not receiving the experience (often referred to as the control group). If the groups differ it would be concluded the experience made the difference. Once an effect has been demonstrated, subsequent research is often conducted to obtain additional information. Control groups receiving different types of experience may be included. The nature of the control groups will determine the possible conclusions one may reach. For example, someone might be interested in evaluating whether the type of book provided to children made a difference. One group could be provided books related to their academic subjects in school, another group provided with age-appropriate “classics”, and a third group with books the children themselves selected. Parametric studies are often conducted to determine how the magnitude of a variable affects the phenomenon. For example, groups of subjects might be provided with 5, 10, 15, or 20 books.

Small-N Designs

If a researcher were seriously interested in testing the hypothesis that providing free books to children improved their academic performance they would obviously recognize that the books would be of no value unless the children actually read them. They might want to test a procedure to determine if it motivated children to read the books which are provided. A group design in which some subjects received the procedure (or different procedures) and some subjects did not could be implemented. Sometimes it is difficult to obtain a sufficient number of subjects to use a group design. This is especially true when working with special populations (e.g., autistic children, the gifted, etc.) or interested in only one or a very small number (e.g., one’s own children). In these instances, it is still possible to conduct an experiment permitting one to conclude cause and effect using a small-N design. One might suspect that it is impossible to conduct a controlled experiment with such a limited sample. That is not the case. Rather than manipulating levels of the independent variable across groups of subjects, small-N designs involve manipulation on each subject.

Establishing the Baseline

Small-N designs require establishing baselines of performance prior to introducing the experimental intervention (see Figure 1.7). Fine-tuning of baseline performance is a critical step and can require many sessions. It is usually necessary to establish consistency of responding (as in the top graph) or responding trending in the direction opposite the expected intervention effect (as in the bottom graph). Although small-N designs require far fewer subjects (thus the name), they can involve similar (or greater) investments of research time due to the number of observations made during the different phases.

Figure 1.7 Fine-tuning the baseline. Consistent responding or responding in the opposite direction of an anticipated intervention effect constitutes a useful baseline.

Although the results may seem compelling, one cannot conclude cause and effect by simply following a baseline condition with an intervention (an AB design, see Figure 1.8). For example, let us say we were monitoring the number of pages a child was reading before going to bed at night. First we would try to establish consistency by putting the child to bed at the same time, keeping the length of reading sessions constant, etc. After the number of pages read each night stabilized we might introduce our planned intervention, perhaps giving “stars” for every 3 pages completed. Even if the number of pages read started to increase dramatically, it would not at this time be possible to conclude the stars made the difference. Although perhaps unlikely, it is logically possible to suggest that something else coincidentally occurred at the time the stars were introduced. Perhaps the book(s) became more interesting, or the weather changed, or the child started drinking orange juice, etc.

Figure 1.8 AB design.

Reversal Designs

Reversal designs (sometimes referred to as ABA, see Figure 1.9) are powerful and popular small-N procedures. In our example, once the intervention results stabilized or continued to increase for several sessions, we could discontinue providing stars. If the number of pages completed then decreased, it would be possible to conclude it was the stars that made the difference. It strains the limits of credulity to suggest that a second coincidence having the opposite effect occurred at precisely this time.

Figure 1.9 ABA reversal design.

Although reversal procedures are the mainstay of small-N designs, there are unusual circumstances where reversals do not occur or where reversing the procedures would be unethical. For example, it is conceivable that after being given stars, the child discovered the intrinsic rewards provided by reading. In that instance, discontinuing the stars would have no effect. The intrinsic rewards would be sufficient to maintain the behavior, a phenomenon known as behavioral trapping (see Figure 1.10). You might think that this is just the result one would hope for. That may be true as one who cares about the child. However, if you are a researcher attempting to establish cause and effect, you are back to square one.

Figure 1.10 Behavioral Trapping. Naturally occurring consequences maintain the changes resulting from intervention.

One might also question the ethics of changing a procedure that was successful in increasing a child’s reading. This concern would be more apparent in research resulting in the child’s increasing a healthy behavior (e.g., wearing seat belts) or decreasing a dangerous behavior (e.g., head-banging). Clearly, in these instances, despite the requirements of science, reversal procedures should not be implemented.

Multiple Baseline Designs

For the unusual circumstances where reversals do not occur or where reversing the procedures would be unethical, variations of multiple baseline designs have been developed (see Figure 1.11). Such designs consist of replications of AB designs across subjects, situations, or behaviors. For example, Tom, Dick, and Mary might be given stars for reading. Stable baselines would be established for each child and the treatment would be introduced at different times for the three children. Instead of working with 3 different children, a similar procedure could be implemented at home at bedtime, at home with the baby sitter, and at school. The third option would be to provide stars for reading, writing, and doing math problems. In all 3 instances, if improvement occurred during the intervention phase for all 3 children, situations, or behaviors, it would be concluded that the stars were responsible.

Figure 1.11 Multiple Baseline Design. Treatment is introduced at different times for different subjects, settings, or behaviors.

This concludes our discussion of the major experimental methods used to study psychology. If you become a psychology major you will be exposed to other, more complicated procedures in graduate research methods courses.

Psychology Research Methods and External Validity

The title of this textbook assumes that our current understanding of psychology informs us about the human condition including our potential as individuals and a species. This assumption is made despite the fact that some of the research findings were obtained with other animals in apparatuses developed for the laboratory. Humans share many characteristics and needs with other animals as we all do our best to adapt to our environmental circumstances. None of us had a choice about where or when we were born, or about the conditions under which we would have to survive and, hopefully, thrive. We all need to adapt to the circumstances we experience as individuals in the journey of life.

Non-Humans as Subjects

The nature of the psychological process under investigation dictates the minimal requirements of an appropriate subject. For example, in order to study perception we not only need a subject capable of sensing and perceiving the environment (see Chapter 3), but also one able to demonstrate that it perceives. The researcher must be able to observe an appropriate response to a specific stimulus. Does this mean that other, less complex animals can be used to study processes applicable to the human being? This is actually an empirical question. One could demonstrate a lawful relationship in a very simple animal (e.g., an earth worm) and test whether the same relationship could be replicated with human subjects.

This issue is similar to the doubts expressed by many at the beginning of the 20th century that vivisection of other animals could tell us anything about human biology or inform surgical technique. In fact, many of the advances in our understanding of human physiology and surgical technique occurring since then would have been impossible if such research had not been conducted. As we shall see, there is much compelling evidence that the same is true with respect to psychology.

Besides being relatively inexpensive to obtain and house, other animals do not raise the same internal validity issues intrinsic to human subjects. That is, they are closer to the perfect spheres we could use to replicate Galileo’s findings with rocks. As we saw previously, we explain differences in behavior as resulting from the interaction between hereditary and environmental variables. Laboratory animals can be purchased from the same litter, thereby having the same genes. They can even be bred or modified for specific characteristics making them ideal for specialized research projects. For example, a colleague of mine studies the learning process in rats infected with the HIV virus (Vigorito, LaShomb, & Chang, 2007). Naturally, for ethical reasons this is a study which could not be conducted with humans despite having important implications and possible beneficial applications. Laboratory animals are often obtained soon after birth and housed under restricted conditions. Obviously, they do not have the extreme cultural and other experiential histories of humans. Also, they are extremely reliable subjects. They do not require phone reminders the previous night in order to show up for a study.

The American Psychological Association has very strict ethical guidelines for the care and use of animal subjects in research. The United States government requires that an Institutional Animal Care and Use Committee be responsible for insuring that all requirements regarding feeding, access to water, climate control, and access to veterinary care are met. One learning textbook author has quipped, “It is unfortunate that there are no similar federal regulations guaranteeing adequate food, a warm place to live, and health care for the human members of our society” (Mazur, 2006, p. 13).

Often choice of species for a research subject is a matter of convenience, expense, and tradition regarding a particular topic area. Laboratory rats are frequently favored for these reasons in addition to the fact that so much is known about their characteristics based upon their research use in other disciplines (e.g., biology). Sometimes, choice of subject is dictated by species characteristics related to a particular area of interest. For example, rabbits have an extra eyelid (nictitating membrane) making them especially suitable subjects for studying the predictive learning of eyeblinks. Pigeons have exceptional eyesight in comparison to rats and are therefore favored as subjects when investigating visual perception.

Experimental Apparatus

The choice of experimental apparatus often hinges on the same issues as the choice of subject; convenience, expense, and tradition. The apparatus must permit observation of a response related to the topic area (e.g., function of part of the brain, perception of a particular stimulus, motivation, learning, etc.). Research apparatuses are considerably different from the natural environments of the species being investigated (see Figure 1.12). It is an empirical question as to whether research findings obtained under these controlled conditions apply elsewhere for these species, let alone tell us anything about the human condition. As we review the empirical findings of the psychology research literature we must constantly remind ourselves of this question.

Figure 1.12 Apparatus to study learning.

All sciences must address both internal and external validity. This is especially challenging in psychology. We do not have the equivalent of perfect spheres as subjects of investigation. Rats, pigeons, chimpanzees, or people often differ from each other in significant ways. The behaviors we study may be complex and difficult to measure. The subjects and laboratory environments we use to obtain control over possible confounding variables are typically very different from the subjects or conditions of real interest. Psychologists are left with two difficult strategies to simultaneously address internal and external validity. They can try to capture the essence of the natural environment and recreate it under more controlled laboratory conditions. The other strategy is to attempt to introduce precise manipulation of the independent variable and measurement of the dependent variable in the natural environment. Throughout this book you will see many examples of the ingenuity of research psychologists in empirically investigating important issues while addressing internal and external validity concerns.

Psychology, Human Potential and Self-Control

A recurring message of this book is that the discipline of psychology uniquely applies the scientific method to study and understand the human condition. It helps us understand why we, more than any other animal, dominate this planet. The human being shares many basic needs and drives with the rest of the animal kingdom and must adapt to its environment in order to survive individually and as a species. Yet the differences in our accomplishments appear do great as to suggest qualitative differences from even our closest DNA relatives.

In the not too distant future, it is likely that communication will occur with the remaining few cultures not significantly impacted upon by current technologies. This could cause us to forget that the biological natural selection process, which continues albeit slowly, evolved over millions of years in an environment that has been significantly altered by human beings. The few remaining indigenous cultures remind us that for almost all our time on earth our everyday needs and experiences were similar to those of other animals.

In the Preface of his book documenting research conducted in the Amazon between 1990 and 1996, Politis (2007) states that his study of the Nukak “probably represents one of the last opportunities to observe a hunter-gatherer society that still lives in a traditional way.” The Nukak, living day to day, have maintained a similar lifestyle for more than 10,000 years. They lack familiarity with government, property, or money. The Nukak do not have a concept of the future and their past history is limited to a few generations. For thousands of years, the Nukak have been adapting to the demands and resources of the Amazonian rainforest. If you or I had been born under such conditions, we would be very different from the way we are and vice versa for the Colombian young adult. Human potential is developed under enormously diverse environmental conditions. Psychology is the discipline which helps us understand how you became the unique individual you are and how you can conceptualize and achieve your potential.

Determinism and Freedom in Psychology

The human condition, whether it takes place in the rain forest or a modern city, may be described as a series of choices. Moment by moment we are confronted by different possibilities. We all have the subjective experience of being free to choose as we wish, whether we are in the rain forest, desert, or modern city. How do we reconcile this feeling with the scientific understanding of the human condition implied by the assumption of determinism? Determinism implies that the subject matter of the discipline is lawful. Thus, through application of the scientific method we ought to be able to discover reliable relationships between hereditary and environmental variables and behavior. If determinism did not hold, none of the research findings described in this book would be possible. Clearly, the research findings support the applicability of the assumption of determinism to the study of psychology.

Choice and Self-Control with Pigeons

For the first of many research studies we will treat in depth, we will examine an experimental study conducted with pigeons with the surprising title “Commitment, choice and self-control” (Rachlin and Green, 1972). Do you think it is possible to scientifically study what are usually considered human characteristics such as choice, self-control, and commitment using pigeons as subjects? Do not the concerns for internal and external validity seem insurmountable? Rachlin and Green (1972) reported the findings of a study manipulating both magnitude and delay of food reward in an apparatus named a Skinner-box, after the scientist who developed it (see Figure 1.13). In a sense, they asked the proverbial question, “Which is worth more, a bird in the hand or two in the bush?” Actually, they asked which is worth more to a bird (pigeon), immediate access to 2-seconds of food or twice as much food after a 4-second delay (see bottom choice in Figure 1.14). The findings were unequivocal. Pigeons almost always chose the red (right) key associated with the small immediate reward rather than the green (left) key associated with the larger delayed reward. Anthropomorphizing, the pigeons appeared “impulsive” rather than displaying “self-control” (i.e., choosing the larger delayed reward over the smaller immediate one).

Figures 1.13 and 1.14 Procedures used to study the effect of magnitude and delay of reinforcement on choice (Adapted from Rachlin & Green, 1972). Pigeons behave “impulsively” (i.e., choose an immediate small reward rather than a larger delayed reward) when confronted with the bottom choice. However, when an initial choice response includes a delay (10 seconds in the example), pigeons are more likely to make a “commitment” (i.e., avoid temptation) to self-control (i.e., selecting the delayed larger reward).This finding, in and of itself, is interesting. However, Rachlin and Green went one step further by adding an initial choice. Pigeons were first confronted with two unlit keys (see left choice in Figure 1.9). Pecking the left key caused it to turn green after 10 seconds. At that point, the pigeon could only respond to the left (now green) key in order to receive 4 seconds of food after an additional 4-second delay. If instead, the pigeon pecked the right key, it was presented with the original choice between the left green and right red keys after the 10-second delay. The surprising finding was that the pigeons were twice as likely to press the left key as the right key.

This result is certainly counter-intuitive. We know that when confronted with the red/green choice, the pigeons strongly preferred red. Why didn’t they initially go right, resulting in the opportunity to make that same choice? Or, why didn’t they initially go right and then press red when provided the original options? The surprising interpretation by Rachlin and Green (1972) is included in the title of their article. By pressing the left unlit key, the pigeons exhibited a “commitment” to a self-control response. By responding in this manner, they were not “tempted” by the red key that was likely to be followed by a response resulting in a small, immediate reward.

Why, one might ask, is the pigeon able to act less impulsively when provided with the choice between the two unlit keys than when presented with the choice between the red and green keys? They usually say that the devil is in the details. This is an instance where the opposite appears true. Something very beneficial is revealed in a detail of the procedures used by Rachlin and Green (1972). It is easy to overlook the 10-second delay that occurred no matter whether the pigeon responded to the left or right unlit key. At that point in time, the choice is not between 2 seconds of immediate food versus 4 seconds of food after a 4-second delay. It is between 2 seconds of food after a 10-second delay as opposed to 4 seconds of food after a 14 (10+4)-second delay. Apparently a 10-second delay is an eternity to a pigeon and the “psychological” difference in a delay of 10 versus 14 seconds is far less than the difference between immediacy and 4-seconds. Since there is a long delay (10 or 14 seconds) no matter the choice between the unlit keys, the pigeon is more influenced by the magnitude of the reward (4 rather than 2 seconds) at that point in time.

One of the objectives of this book, is to encourage the development of a scientific schema as a way of evaluating scientific (and many non-scientific) questions. All sciences use similar formats in research articles. They generally consist of: introductions placing the study within the context of prior research; method sections providing sufficient detail to replicate the procedures; reporting of results and statistical analyses; discussion of the conclusions, implications, and limitations of the research. In order to assess whether you understand the Rachlin and Green study (or any other research), you should ask yourself the following: What was the question being addressed by the investigator(s)? How did the procedures enable the question to be addressed? What were the results and conclusions regarding the question? In this instance you should be able to:

Choice and Self-Control with Humans

Rachlin and Green’s findings have been replicated many times, attesting to the internal validity of the findings. That is, we know that that there is a cause-effect relationship between delay of reward and choice behavior in pigeons. The question remains, however, whether these results relate to human behavior. Walter Mischel developed the “marshmallow test” to study impulsiveness and self-control in children (Mischel and Ebbesen, 1970; Mischel, Ebbesen, and Raskoff Zeiss, 1972; Mischel and Yates, 1979; Mischel, Shoda, and Peake, 1988; Mischel, Shoda, and Rodriguez, 1989; Shoda, Mischel, and Peake, 1990). An adult placed a single marshmallow in front of a child with the instruction that it could be eaten immediately or if the child waited a certain amount of time (e.g., 20 minutes), a second one would be provided. There are many amusing and interesting You Tube videos of children undergoing the marshmallow test and implementing strategies to avoid giving in to temptation. Children who distracted themselves (e.g., by playing with a toy) were more successful than children who focused upon the marshmallow. Importantly, Mischel and his colleagues found the ability to delay gratification by 4-year olds to be significantly related to their later success in life as indicated by such measures as school performance, SAT scores, completion of college, and interpersonal competence.

It has been demonstrated that self-control can be learned. Mazur and Logue (1978) first trained pigeons to choose a large delayed reward over a small delayed reward (which is obviously easy to do). Over the course of a year the pigeons were taught to gradually adapt to increasingly shorter delays of the smaller reward. When tested a year later, the pigeons continued to exhibit a preference for large delayed rewards over small immediate ones (Logue and Mazur, 1981). These same findings were obtained with children provided similar training (Schweitzer and Sulzer-Azaroff, 1988). Given the documented importance of self-control to success later in life, it would appear prudent to incorporate such training as early in life as practicable for all children. Logue (1995) has written an excellent review of the self-control literature including applications to eating disorders, substance abuse, money management, studying, and interpersonal relations.

Many human problems occur as the result of choosing immediate small rewards rather than delayed, but more significant rewards. Examples include: eating an ice-cream sundae despite trying to lose weight; excessive drinking, threatening one’s (and others’) safety; smoking a cigarette (“slow-motion suicide” according to one Secretary of Health); hitting one’s spouse or a child because it immediately stops them from bothering you even though it creates much larger, delayed family problems; or, horror of horrors, checking out Facebook or playing video games instead of reading this book! Rachlin and Green’s (1972) results suggest that each of these problems may be addressed by committing oneself to a course of action in advance. For example: shop from a list including only nutritious, non-fattening foods; don’t drive past the ice-cream store; don’t go to the bar, or make sure you have a “designated driver”; stay away from places or events where you are likely to smoke; imagine the behaviors that upset you and rehearse a better coping strategy; use a daily planner for time-management and write the title of this book all over the pages (only kidding).

There is a substantial research literature attesting to the importance of self-control skills. It has been demonstrated that 8th-graders’self-discipline scores were more predictive than IQ for school attendance, homework time, and final grades (Duckworth and Seligman, 2005, 2006). Wills and his co-workers have documented that self-control skills reduce the risk of tobacco, alcohol, and marijuana abuse in 9-year-olds, middle-, and high-school students (Wills, Ainette, Stoolmiller, Gibbons, and Shinar, 2008; Wills, Ainette, Mendoza, Gibbons, and Brody, 2007; Wills, Walker, Mendoza, and Ainette, 2006; Wills and Stoolmiller, 2002). College students who avoid and seek alternatives to situations associated with heavy drinking have been shown to consume less alcohol (Sugarman and Carey, 2007). Thus, to a large extent, success in life appears related to the ability to resist short-term temptations in order to achieve long-term goals.

Different parenting styles will be described in Chapter 8. Mothers’ manner of instruction and level of emotional support for their preschoolers were shown to later relate to their children’s behavioral control and task persistence in school (Neitzel and Stright, 2003). Religiosity as well as the quality of parent-adolescent communication has been shown to relate to substance abuse and sexual behaviors in African American adolescents (Wills, Gibbons, Gerrard, Murry, and Brody, 2003). A major review article addressed the relationship of religiosity to self-control. It was suggested that religion promotes self-control by encouraging self-monitoring and attainment of behavioral goals (McCollough and Willoughby, 2009).

Despite the fact that we and the Nukak experience very different human conditions, there is no reason to suspect that they feel less “free” than we do in striving to reach their goals and realize their potential. From our perspective, however, we might question whether this is true. Do not the constraints of the rain forest as well as the limitations of their educational experiences result in our being able to think about things, feel things, and act in ways that they cannot? And, is not the reverse also true since we have such limited experience in the rainforest in comparison to them? Is it not true that none of us is “free” to do whatever we wish, live however we want, or become whomever we choose? Psychology provides a lens through which we may ponder the potential of the human condition from the perspective of individuals and our species.

What should I do, how should I live, and who should I become? These are the questions Haidt (2006) considered fundamental to human happiness. In a sense, one becomes freer by accepting that you are a lawful part of nature. It means that you can apply the principles of psychology to yourself in order to accomplish your own objectives. This places you more in control of your life. Is that not what we mean by freedom?

The importance of the “self” in self-control must be recognized. That is, “goals” are subjective and must be defined by each individual for her/himself. This thought is recognized in the most famous quote from The Declaration of Independence: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness.” You have the ability to apply self-control techniques to influence what you do, how you live, and ultimately who and how happy you become.

Practicing Self-Control

I describe psychology as a discipline enabling humans to achieve their potential as individuals and as a species. That is clearly a bold and ambitious claim. At the end of many chapters, I will suggest you test this claim by engaging in a self-control project. As a by-product, I hope you acquire knowledge and skills which facilitate your transition to college and serve you well throughout your life. You will be asked to act like a professional psychologist. Your initial reaction might be “Is that ethical?” The answer would be “yes” if you are not only the “psychologist” but also the “client.” For years, I have been assigning self-modification projects in some of my classes. These are not only do-it-yourself projects, but also do-it-to-yourself projects. It is an instructive assignment requiring the student to observe her/his own behavior, develop a plan to change in a desired way, and assess progress. In addition to the instructional benefit, a very high percentage of the projects are successful. This is exactly what one would expect if psychology as a science was successful in discovering reliable ways of changing behavior. Note the advantage you have when you are both “client” and “psychologist.” It is logistically problematic, if not impossible, for someone else to monitor your overt behavior every waking moment. It is absolutely impossible for someone else to monitor your covert behavior at all. Despite your friend’s belief that she/he “feels your pain” or can “read your mind”, only you have direct access to your feelings and thoughts. The best your friend can do is to make inferences about your feelings and thoughts based upon how you overtly behave. You have a distinct advantage over anyone else in influencing how you feel, think, or behave.

Defining and Measuring Your Goals

Often, individuals fail to identify circumstances as requiring self-control and thereby fail to act in their long-term self-interest (Myrseth and Fishbach, 2009). Within the context of self-control, this means you would like to change the way you behave, feel, or think under specific circumstances.

The first step in self-control is to objectively describe your current and desired behaviors. Vague descriptions such as I want to be in better shape, be neater, or control my anger, etc., are not sufficient. As described earlier, psychology relies upon observable and measurable observations of behavior. Response measures typically consist of the frequency, amount, or duration of the target behavior. Following is an alphabetical listing of self-modification project response measures recently submitted by my students:

Behavior	Response Measure(s)	Type
Anger	instances/week	Frequency
Anxiety	subjective units of distress	Amount
Cigarette smoking	number/day	Frequnecy
Cleaning room	minutes/week	Duration
Clutter reduction	items on desk	Amount
Coffee consumption	ounces/day	Amount
Credit card spending	dollars/week	Amount
Drawing	minutes/day	Duration
Exercise	minutes/day	Duration
Exercise	repetitions	Frequency
Knuckle cracking	times/day	Frequnecy
Measurements	inches	Amount
Meditation time	minutes/day	Duration
Nail & cuticle biting	length of nails	Amount
Piano playing	minutes/day	Duration
Punctuality	minutes late/instance	Duration
Reading	pages/week	Amount
Sleep	hours/night	Duration
Smoking	cigarettes/day	Frequency
Social Avoidance (shyness)	subjective units of distress	Amount
Social network use	times/day	Frequency
Social network use	hours/day	Duration
Soda consumption	ounces/day	Amount
Studying	minutes/day	Duration
Task completion	number/day	Requency
Television viewing	hours/day	Duration
Time management	percentage/tasks completed	Amount
Video game use	hours/day	Duration
Weight	pounds	Amount
Worrying	instances/week	Frequency
Writing	pages/day	Amount

Collecting Baseline and Intervention Data

Once response measures have been decided, it is possible to start data collection. Fulfilling the objective of a self-control project requires being able to determine whether an intervention is working. One must therefore collect baseline and intervention data. Unlike the Small-N designs described previously, there is no need to determine cause and effect. It is not necessary to include a reversal phase or a multiple baseline. It is only necessary to demonstrate an improvement in the target behavior. The only instance where a baseline is unnecessary is when the behavior does not occur at all. For example, some students report never exercising before starting their self-control project. Recall that a good baseline is either stable or moving in the wrong direction. Once that is attained, improvement (or lack thereof) will become apparent when graphing the intervention data. Sometimes, just the act of assessing and graphing baseline data leads to improvement (Maletsky, 1974). Often my students reported that the requirement to record instances of their problem behavior focused their attention in such a manner that their behavior changed. You might recall that this would be an example of reactivity. Several experimentally verified intervention procedures will be described in Chapter 5 (Direct Learning). You might be able to derive your own procedures based upon the Rachlin and Green (1972) findings or by consulting the extensive empirical self-control literature. There will be additional suggestions concerning possible self-control projects in subsequent chapters.