An Introduction to Psychology:
The Science of Mind and Behavior

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Several studies have found that boys with several older brothers have a greater probability of developing a homesexual orientation than are boys with one or no older brothers (Motluk, 2003). [MAKE A GRAPH OF # OF OLDER BROTHERS AGAINST ORIENTATION].

We tend to form beliefs easily, based on little or no critical evaluation of the relevant information. We do this because we generally are not aware of how easy it is for error to enter into the process of belief formation. For example, ... COGNITIVE ILLUSIONS

[Note: Whenever the symbol ∂ appears, click on the link and you will be taken to a definition of the word immediately preceding the symbol. The glossary for the textbook can be found here.]

What is Psychology?

[Psychology is the] diagnosis, treatment and prevention of mental, emotional and behavioral disorders. Psychological counseling is provided by one who is trained in methods of psychological analysis, therapy, and research. (WRH Health System)

As indicated in this definition taken from a hospital web site, many people think of psychology solely as a health-related profession with one major goal: to help people change their maladaptive[∂] cognitions[∂], emotions, and behaviors to more adaptive[∂] ones, thereby helping them to lead more fulfilling and satisfying lives. According to this definition, psychologists are somewhat like expert "explorers of the disordered mind": they are trained to seek and identify the hidden mental causes of disturbances in thinking, feeling, and behaving. In this view of psychology, psychologists facilitate positive changes in their personalities by helping clients[∂] to realize and "work through"[∂] the mental causes of their maladaptive cognitions, emotions, and behaviors.

Psychology as a mental-health profession is exemplified[∂] in the following transcript of a therapeutic session with a 33-year-old schizophrenic patient given the pseudonym[∂], "Joseph," who was raised in a town in the north of England (identified in the passage as “F.” in order to protect Joseph's anonymity[∂]), had been a shy and solitary person since childhood. However, he did not develop severe symptoms of schizophrenia until he was 26. In speaking of this, Joseph stated:

If things get worse I won’t be able to cope with my direction gear. I see myself heading for the life of a recluse, being valued at 7 and 1/2 pounds per calendar month.
(Barham, 1984, p. 101)

Joseph's thinking here seems disorganized and confused, which is a major symptom of schizophrenia. Two other major symptoms of schizophrenia are delusions[∂] — false beliefs (such as believing that others are trying to destroy one) — and hallucinations[∂] — perceiving things that are not real (such as hearing the voices of nonexistent people). When asked about his parents, who presumably still lived in F., Joseph reported that no one lived there any longer:

Joseph: It’s impossible to live there now. It’s just solid rock you know. You couldn't live there. It’s just dust you know. You see, you can’t live anywhere you know, you've got to have the weather conditions to live in. I mean if you buy a house and find you can never go out of the house. If you buy a house on dry land like, you find that you’re never out of the house.
Therapist: Why?
Joseph: Why, because if you go outside you get dust up your nose and down your throat.
Therapist: In F.?
Joseph: Why anywhere, don’t you. ([Joseph said this] with some irritation)
Therapist: So, we’re not just talking about F.?
Joseph: No, even here. What they do is they get a pressure suit when you take seriously ill and you have to live on tablets. And when you take seriously ill they put you on a crash course in a pressure suit and you go crazy altogether, crackers altogether, for about three weeks. There’s one on M15s [the ward that contains the most seriously ill mental patients in Joseph’s hospital]. That’s psychiatry that. You see the whole world is, you see there’s so much dust and dirt and things like that, you can’t live. Most people live in communities under big domes. Now you don’t know the dome is there. They build a whole village, and then they build a dome over the top, and they paint the dome and you see aeroplanes flying about inside.
Therapist: Inside the dome? And what is there outside the dome?
Joseph: Certain death. There’s domes under the sea.
(Barham, 1984, p. 115; altered slightly)

Joseph's delusional and disorganized thinking are clearly demonstrated in this passage; and they indicate that he is suffering from schizophrenia, which is one of the psychotic disorders[∂]. People who suffer from schizophrenia typically are given biological therapies[∂] in the form of antipsychotic medications, which reduce the symptoms of psychosis. They also typically receive some form of psychotherapy[∂], which helps them to cope with the negative consequences of schizophrenia on their everyday lives.

Although most lay people think of psychology solely as a mental-health profession, it is in fact a discipline[∂] that studies a wide range of phenomena[∂]. Unlike many other academic or professional disciplines (such as history, medicine, philosophy, mathematics, biology, law, or economics), psychology actually consists of two distinct subdisciplines:

1. Professional psychology. As just stated, psychology is, in part, a mental-health profession — with its workers located primarily in clinics[∂] — that has as its main goal that of developing and using therapeutic techniques, advice, or guidance to help people with cognitive, emotional, behavioral, interpersonal, occupational, or academic difficulties to function better in everyday life.
2. Academic psychology. Psychology also is, in part, a behavioral science — with its workers located primarily in colleges, universities, and research institutions — that has as its main goal that of using a scientific approach to better understand the causes of mental events and behavior.

The two subdisciplines are distinguished because each places a greater emphasis on achieving its respective goal compared to the other. Nevertheless, it should not be inferred[∂] that scientific research is never a concern of professional psychologists or that mental-health applications are never a concern of academic psychologists. There is some overlap between the two subdisciplines, although probably not as much as is needed (see, for example, the critique[∂] by Tavris, 2003) — a limitation that will be discussed in several parts of this textbook.

What is Professional Psychology?

Although professional psychology first emerged soon after the turn of the twentieth century (Caplan, 1998; Witmer, 1907), it did not develop into a major subdiscipline within psychology until soon after the end of World War II (Freedheim, 1992). From that time to the present, professional psychology has grown tremendously in size and influence, not only within psychology, but also within western (especially American) societies. The psychological fields[∂] referred to as counseling psychology and clinical psychology are the disciplinary "homes" of professional psychology. In general, the field of clinical psychology focuses on classifying, researching, and treating moderate to severe mental disorders; whereas the field of counseling psychology focuses on providing assistance and guidance to those struggling with interpersonal, occupational, academic, and other everyday difficulties. You will learn more about the causes and treatments of mental problems, disturbances, and disorders in later sections of this textbook.

What is Academic Psychology?

Academic psychology first emerged during the second half of the nineteenth century, when it was referred to as experimental psychology (or simply as the new psychology; Dewey, 1884) because of its focus on designing and performing controlled experimental research — often in laboratory settings — to study the functioning of the conscious mind. Experimental psychologists were most interested in using a scientific approach to study the mental functions of sensation, perception, learning, and memory. A very early example of a scientific approach to the study of consciousness may be seen in the work of Theodor Bischoff (pronounced Tay-ah-dor Bish-off), a nineteenth-century physiologist who experimentally tested a claim[∂] about consciousness made earlier by Pierre Cabanis (Pee-air Cah-bah-nee), an eighteenth-century scientist. In 1795, Cabanis speculated that consciousness requires a physical connection between the brain and the rest of the nervous system. If this hypothesis[∂] were true, Cabanis and Bischoff reasoned, then consciousness should end if the brain is separated from the rest of the body. According to Hothersall (1995):

Bischoff ... arranged a macabre, even ghoulish, test of Cabanis’s assertion[∂] on the head of a newly executed criminal [decapitated by guillotine]. Even intense stimuli, including the shouted word Pardon! elicited no reaction ... after decapitation. Cabanis ... was correct. (p. 81)

Of course, there are other possible explanations for the lack of response on the part of the prisoner's head. For instance, the shock of having his head cut from the rest of his body may have interfered with the prisoner's motivation to respond. Nonetheless, Bischoff's study was scientific because it was performed according to the following two scientific precepts[∂].

Study Questions 1-1

1. How would you define the two subdisciplines of psychology in your own words?
2. In what ways do the two subdisciplines differ from each other?
3. In what ways are the two subdisciplines similar to each other?
4. What does it mean to say that the two subdisciplines complement one another?

Scientific Precept #1. Although you might not accept Bischoff's experiment[∂] as adequate support for Cabanis' theory, his attempt to find supporting evidence illustrates one major precept of modern science:

Claims must be tested empirically — they must be tested
by making direct observations of physical events.

Empiricism is the doctrine that knowledge can be derived only from sensory experience — from direct observations and measurements of events. For example, if someone claimed that there are 23 people in a classroom, an empirical test of the claim would involve performing a direct count. If a different number were counted, this would lead us to question the original claim. Nevertheless, we would not yet reject the original claim because, even though we performed an empirical test, the observer's count may have been wrong: some of the people in the classroom may have been hiding, the observer may not have known how to count correctly, the observer may mistakenly have counted some people twice, etc. Thus, empiricism is necessary for a scientific approach, but care must be taken to increase the chances that the observations and measurements are accurate. Furthermore, regardless of how much care is taken, it still is possible that these observations and measurements are inaccurate. This is an important point that will be discussed throughout the textbook.

fideism--the doctrine that knowledge involves faith or comes from revelations (by authorities).
rationalism--the doctrine that knowledge comes from reasoning independently of experience.

Scientific Precept #2. A person using a scientific approach does not accept a claim simply because it is asserted[∂] to be true, even if that individual states that she is "absolutely certain." A person using a scientific approach knows that there always is room for doubt, especially when the initial claim was not developed through empirical means. For example, if it is important to know precisely how many people there are in a classroom, it would be unwise to accept without question someone's assertion that the room contains 23 people. This illustrates a second precept of modern science:

Claims are doubted — that is, they are not accepted as likely to
be true — until there is adequate evidence to support them.

Skepticism is the doctrine that claims are to be doubted until the evidence supporting them has been publicly reported and judged by independent evaluators to be adequate. Once the evidence is judged by most competent evaluators to be adequate, the claim is accepted as likely to be true. Nevertheless, new evidence still may cause scientists to rethink whether the claim actually is true or not. An example of this will be provided below.

Those using a scientific approach to test claims combine both skepticism and empiricism when testing claims: a claim must be tested empirically a number of times by different researchers with different approaches before accepting the probable truth of the claim. The more that this is done, the more confident we can feel that the claim is likely to be true. For example, a geneticist by the name of Peter St. George-Hyslop has, for years, looked for genes associated with the development of Alzheimer's Disorder. In talking about the recent discovery of a gene thought to be a cause[∂] of the disorder, St. George-Hyslop referred to the "Eureka (Aha!) Moment" — the point at which the increasing accumulation of supporting evidence finally tips a person over to accepting a claim as likely to be true:

The "Aha!" moment happens to different people at different times.... We are aware of little bits of data[∂] as they come out that say, "Yes, it's real," but not very strongly, so what you get is not really a eureka moment but something that is incremental. It starts out as "Uh-huh, but it's probably a fluke," to "Maybe it's not a fluke," to "This could be real, let me see what I can do to make it go away," to "Well, it seems pretty robust, but there are still problems," to "We've taken this as far as we can and we concede that there are many things to do on this story, but before we do too much more it needs to be put in the hands of some other people, with totally different data sets and totally different ways of analyzing things. and see if they get the same results." (quoted in Halpern, 2005)

As you can see, a skeptical empiricist takes his or her time before finally accepting a new claim as likely to be true (or rejecting it as likely to be false). St. George-Hyslop mentioned several steps in the process:

1. Observations, which may be inaccurate or may have occurred simply by chance, suggest that a claim should be examined more closely. For example, flipping a coin five times and getting five heads in a row suggests that the coin may be unfair. On the other hand, the results could have been a "fluke" (that is, could have occurred by chance).
2. Further observations suggest that perhaps the initial observations were not inaccurate or did not occur by chance. Flipping the coin five more times and getting four heads and one tail provides some reason to think that the coin really is unfair. Again, however, it still could have been a "fluke."
3. Further observations provide even more support for the claim, which suggests strongly that it may be true. Flipping the coin five more times and getting four heads and one tail provides even more support for the claim that the coin is unfair. On the other hand, it could be something about the way in which the person is flipping the coin or something else going on in the room that is affecting the way the coin rolls in the air.
4. Now is the time to determine if there is something else going on that is making the claim appear to be true when it actually is false. In other words, it is time to try to "falsify" the claim: to set up a situation in which, if the claim actually is false, then the observations will demonstrate this. If the high percentage of heads found has to do with how the "flipper" was flipping the coin, then, if he flips a different coin, he still should get more heads than tails. On the other hand, if his method of flipping has nothing to do with the results, then, when he flips the other coin, he should end up with about 50% heads. Let's say that the percentage of heads with the new coin is around 50%. Thus, we can conclude that the observations with the first coin, where heads came up about 87% of the time, are unlikely to have been due to the way that the coin was flipped.
5. Other researchers try to replicate the observations and to falsify the claim. Now, other people in other locations and with different attitudes about the possible truth of the claim make their own observations with the coin. If their observations continue to support the claim, then we can feel confident that the claim is very likely to be true. On the other hand, if some or all of the others make observations that contradict the claim, then we cannot feel much confidence that the claim is true. In this case, there probably were unobserved factors that made the claim appear to be true when it actually was not. If the question is important enough, researchers would begin to look for these other factors.

In the example of the number of people in a classroom, a skeptical empiricist would insist on making direct observations of the room's inhabitants before accepting the claim (that there are 23 people) as likely to be true. If he or she counted 23 people, the skeptical empiricist would insist on a second count, just in case a mistake was made during the first count; and perhaps also would insist on a third count, fourth count, fifth count, and so on, if he or she deemed an accurate count to be of great importance. As the number of counts increased, and if 23 people were counted each time, a skeptical empiricist would place more and more confidence in the claim that the classroom contained 23 people. If, after completing 1000 counts, he or she observed 23 people on 997 counts, 22 people on 2 counts, and 24 people on 1 count, the skeptical empiricist probably would conclude that it was virtually certain that there are 23 people in the classroom (and that mistakes had been made on three counts).

Nevertheless, regardless of the number of times that 23 people were counted, a skeptical empiricist would (or should) never say that "it has been proved" that there are 23 people in the room. Why? Because of the possibility — small as it may be — that a mistake was made each time that 23 people were counted. Before you dismiss skeptical empiricists as obviously insane ("How many times do you need to repeat the count before you'll agree that there definitely are 23 people in this room?!?!"), let's look at an instructive example from the history of human-genetics research.

Study Questions 1-1

5. How would you define empiricism in your own words?
6. What is an example from your own life of a time when you were being empirical when trying to answer a question?
7. How would you define skepticism in your own words?
8. What is an example from your own life of a time when you were being skeptical of a claim made by someone else?

For over 25 years — from the late 1920s until 1955 — it had been repeatedly observed that each cell in the human body contained 48 chromosomes[∂] (excepting certain cell types, such as mature reproductive cells — sperm and ova — which were found to have only 1/2 that number). As dictated in the steps outlined above, this claim was tested repeatedly by many biologists working in different laboratories in different countries. Thus, the claim that humans have 48 chromosomes in each cell was accepted as very likely to be true. In fact, this number was observed so often under so many different conditions and by so many different observers that biologists accepted it as an established fact[∂]. By the 1950s, biologists counting a different number of chromosomes concluded that they had counted incorrectly (Kevles, 1985), just as people counting something other than 10 fingers on a pair of normal hands would conclude that they must have made a mistake.

In 1955, however, Joe-Hin Tjio used an improved technique for preparing cell nuclei[∂] on slides, which spread the chromosomes apart so well that each could be clearly identified for the first time (Tjio & Levan, 1956). Tjio counted only 46 chromosomes in each cell. He repeated the counts many times with chromosomes from many cells and kept observing only 46 chromosomes. He also asked others in the laboratory to count them. They also counted only 46 chromosomes. In other words, Tjio found that the chromosome number that had been repeatedly observed and reported in every scientific article published on the topic for over a quarter of a century had been wrong.

Why did so many researchers during this time period repeatedly count the wrong number of chromosomes? Although each was being properly empirical in his or her research, their primitive chromosome-preparation techniques resulted in a clump of intertwined chromosomes that could not be distinguished easily. Thus, counting the number of chromosomes in this clump involved a great deal of subjectivity[∂]: the count depended on a number of arbitrary and idiosyncratic[∂] factors limited to the individual doing the counting — factors such as preconceptions, personal feelings, whims, tastes, or uninformed opinions. Because of these subjective factors, researchers might count one chromosome as two, especially if it had been cut in half and placed on two different slides; or count two chromosomes as one, especially when they were clumped together. Researchers used their laboratory experience and intuition, which (as we will see throughout this textbook) often introduce significant inaccuracies: our personal experience and intuition rely too strongly on subjective factors. If empirical data are to provide unambiguous evidence for or against a claim, the observations made must be as objective[∂] as possible: the observations must not depend on personal preferences, preconceptions, or biases. This is why instrumentation often is used by scientists to measure phenomena. Observations also must be repeatable and verifiable[∂] by others.

If the original techniques were inadequate for clearly distinguishing the chromosomes and if the identification of individual chromosomes was strongly influenced by subjective factors, why did virtually every biologist who published their observations report counting 48 human chromosomes? The probable answer can be illustrated by the experience of a biologist, Tao-Chiuh Hsu, who, several years before Tjio made his observations, also used an improved technique that allowed him to clearly distinguish and identify each chromosome. Hsu stated that he "had difficulty getting the count to equal forty-eight" chromosomes (Kevles, 1985, p. 241). In other words, he kept counting 46 chromosomes; but, because of his preconception[∂] that there should be 48 chromosomes, he kept repeating his counts until he was able to observe the "correct" number. Hsu's experience is an excellent example of what has come to be called the confirmation bias, which is the tendency to accept without question the accuracy of evidence that agrees with (confirms) one's preconceptions; and to question the accuracy of evidence that contradicts (disconfirms) one's preconceptions. The disconfirming evidence — such as Hsu's counts of 46 chromosomes — is examined very carefully until problems with the evidence are found. If these problems seem, at first, to be relatively minor, they are distorted and exaggerated until they appear significant. At this point, the disconfirming evidence can be rejected and, hence, ignored. Since the confirming evidence is not subjected to a similar scrutiny, it is readily accepted and used to support the preconception. The psychologist, Thomas Gilovich (1991), described the confirmation bias in this way:

When examining evidence relevant to a given belief, people are inclined to see what they expect to see, and conclude what they expect to conclude. Information that is consistent with our pre-existing beliefs [preconceptions] is often accepted at face value, whereas evidence that contradicts them is critically scrutinized and discounted. Our beliefs may thus be less responsive than they should to the implications of new information. (p. 50)

The confirmation bias leads us to not examine confirming evidence for its faults, which means that we won't find problems with this evidence, even when these problems are relatively obvious to anyone who took the time to look. For example, when researchers counted 48 chromosomes in their preparations, they accepted without question that this observation was accurate because it agreed with their prior belief that there were 48 human chromosomes. The confirmation bias also leads us to examine closely disconfirming evidence for its faults, which means that, if they exist, we will find them; and, if they don't exist, we still may find minor problems that may cause us to question the evidence more than we should. For example, when researchers counted something other than 48 chromosomes in their preparations (such as the correct number, 46 chromosomes), they assumed that this observation was inaccurate because it disagreed with their preconception that there were 48 human chromosomes. Often, they recounted until they felt satisfied that the cell contained 48 chromosomes (that is, they distorted their observations); or, if they still were unable to count 48 chromosomes after repeating their observations a number of times, they probably would have discarded the data because, in their minds, the slide containing the chromosomes must have been improperly prepared. This is what Hsu meant when he said that he "had difficulty getting the count to equal forty-eight" chromosomes. He had to work hard either to misperceive the evidence until it seemed to agree with his preconception or to find a reason to reject the evidence as inaccurate.

The fact that we don't subject the confirming evidence to the same degree of examination and evaluation as we do the confirming evidence means that we are unlikely to reject our preconceptions. Instead, our preconceptions are likely to become stronger and stronger over time. Let's look at an example of the confirmation bias in psychology and psychiatry in the creation of the mental disorder known as Premenstrual Dysphoric Disorder.

Study Questions 1-1

9. Why should a skeptical empiricist never conclude that a claim has been proved to be true?
10. How does subjectivity limit our ability to be empirical when collecting evidence?
11. How would you define in your own words the "confirmation bias"?
12. How does the confirmation bias limit our ability to properly test whether a claim is (probably) true or not?
13. What would be an example of a subjective observation of an individual's
    (a) amount of intelligence,
    (b) amount of hunger,
    (c) degree of interest in a visual stimulus,
    (d) level of sexual desire.
14. What would be an example of an objective observation of an individual's
    (a) amount of intelligence,
    (b) amount of hunger,
    (c) degree of interest in a visual stimulus,
    (d) level of sexual desire.
15. In what way does the history of research on the number of human chromosomes illustrate the negative influence of subjectivity and of the confirmation bias?
16. In what way does the history of research on the number of human chromosomes illustrate the negative influence of the confirmation bias?

What is the Relation Between Mind & Body?

Philosophical Speculations
The field called biological psychology is concerned with explaining cognitions, emotions, and behavior in terms of physiological processes, especially those occurring within the nervous system (the brain, spinal cord, and nerves). The belief that mental processes can be explained completely by physiological processes has existed since at least the emergence of academic psychology during the second half of the nineteenth century. Experimental psychologists of that era often worked within departments of philosophy and thought of themselves as "scientific philosophers." Their goal was to study scientifically the fundamental nature of the conscious mind — one major focus of philosophical theorizing during that time period. In order to accomplish this goal, experimental psychologists used research techniques and procedures borrowed from the science of physiology (the biological science that studies the physical functioning of organisms). Thus, academic psychology originated in a blending of the experimental methods of physiology with the speculative theories of philosophy. Because of this dual influence, it is not surprising that experimental psychologists assumed that there was a close relationship between the workings of the nervous system — and especially the brain — and the workings of the mind. It was the nature of this relationship that many experimental psychologists sought to understand.

The philosophical influence on experimental psychology has very ancient roots, however. In his history of psychology, Gardner Murphy (1949) reconstructed what he believed to be the earliest influence on modern psychology — ancient religious concerns with the nature of the human soul or spirit:

While primitive [that is, ancient] cultures differ as much in their psychology as they do in their basketry and pottery, ... they show a general preoccupation with one recurrent problem — the nature and attributes of the soul. The dramatic difference between a sleeping and waking man invites the thought that something has gone out and then returned. The awakening man may recount a battle in which he took part [in a dream] while ... his body lay still upon the ground [in sleep]. In illness, especially in delirium or coma, something seems to disappear which may, upon recovery, reappear. The conception of a psychic entity — a detachable soul, we might say — makes sense to him. (p. 5)

According to Murphy, early humans probably thought that this "detachable soul" contains our fundamental human nature. Furthermore, if the soul is “detachable” from the body, thereby allowing it to survive the body's death, then the soul's essence[∂] must differ from that of the body. Lastly, if we locate the human mind within the nonphysical soul, then the mind's essence also must differ from that of the body.

This train of thought, however, raises a problem: if the mind and body are essentially distinct, how can one influence the other? For example, if a pin is stuck into a finger, how can the mind, which consists of a nonphysical essence, experience pain, which reflects the damage caused to the physical essence of the body? Or, in a similar way, if the mind decides that it wants to go somewhere, how can it cause the body, which consists of a physical essence, to walk to that location? These seemingly unanswerable questions are examples of what is referred to as the mind-body problem (see Figure 1). The mind-body problem became a significant impediment to the emergence of a scientific psychology primarily because of the philosophical musings of a French philosopher and mathematician of the seventeenth century, Rene Descartes (1596-1650; pronounced Reh•nay Day•kart).

Figure 1. The Mind-Body Problem

In effect, Descartes probably helped to delay the emergence of the behavioral sciences by making a very explicit and extreme distinction between the mind and the body. In his doctrine of mind-body dualism, Descartes asserted that the mind consists of a nonphysical (supernatural) essence, whereas the body consists of a physical (natural) essence. According to Descartes:

1. The mind functions through nonphysical thought alone, whereas the body functions through a number of physical processes (for example, processes involved in sensory stimulation, walking, reproduction, and digestion).
2. The body can be understood only through the study of physical events and processes (nature), whereas the mind can be understood only through the study of nonphysical events and processes (supernature).
3. The workings of the body ultimately are caused by physical forces external to it, whereas the workings of the mind are self-caused.

In other words, Descartes conceived of the body as a machine controlled by natural (physical) processes, whereas he conceived of the mind as a supernatural entity that was entirely separate from the natural processes making up the physical universe. Because of its supernatural essence, the mind is characterized by free will: its choices are unaffected by causal factors external to itself, including causal factors in the natural world. In other words, the mind causes itself and, therefore, can choose any course of action it wills.

Descartes believed that only humans have supernatural souls and, hence, have free will. In his view, nonhuman animals are simply bodily machines whose behaviors are determined solely by external physical forces; and, therefore:

the difference between humans and animals so important to the Christian religion was preserved. Also, animals were thought [by Descartes] to be devoid of feelings. How could they have feelings if they did not have souls? Descartes dissected live animals, before anesthesia was available, and was described as “amused at their cries and yelps since [he concluded] these were nothing but the hydraulic hisses and vibrations of machines.” (Schultz & Schultz, 1987, p. 26)

In this passage, we see that Descartes reasoned that, because nonhuman animals have no supernatural souls, their behavior is completely determined by external natural causes. Determinism refers to the philosophical doctrine[∂] that an event is caused by a sequence of prior events. For example, when someone shoves you hard, you fall over. Your behavior is not the result of free will (you didn't choose to fall over): it was caused by a prior event (the shove) that came from an external source (another person). Descartes stated that many human behaviors can be determined, just as with the behavior of nonhuman animals, because our bodies are physical machines just as their bodies are. Thus, humans express a number of automatic reflexive responses to prior physical events, such as reflexively withdrawing a finger from a hot stove. Nevertheless, Descartes argued that humans also are able to freely will their behavior because humans have self-caused supernatural minds.

By conceiving of the mind as a supernatural entity, Descartes' philosophy convinced people that it could not be understood with a scientific approach. Because of the mind's spiritual essence, it has no causes outside of itself that could be studied scientifically. In other words, according to Descartes' philosophy, the causes of mental events could be neither investigated empirically nor explained by the natural processes. Instead, because the mind itself functioned only through thought, it could be understood only through thought — through introspection[∂] — and then reasoning about the results of introspective thinking. Thus, after the publication and dissemination of Descartes' philosophy during the 1600s, scientific studies of humans focused exclusively on investigations of bodily structures, states, and processes. One historian of psychology put it this way:

although man [as a physical body] was encompassed by the world of science, human nature [that is, the nature of the human mind] was not. As a purely physical system, man was subject to universal physical laws. Everything [else] about man ..., however, was untouched and even implicitly negated by the physical sciences. Thinking, experiencing, and acting were events not touched by physics and chemistry, and since physical laws were universal and comprehensive, these mental events were scientifically somehow unreal. (Mackenzie, 1976, p. 332)

The widespread acceptance of Descartes’ mind-body distinction made it impossible to develop a scientific psychology for more than two centuries.

Biological Knowledge
Over the next 200 years, from about 1650 to 1850, the scientific investigation of the human body led to the development of a large amount of knowledge about the structures of the body, their functions, and many essential physiological processes. Of most importance in this course was the gradual development of knowledge about the main structures of the nervous system and their primary functions, especially discoveries about the influence of brain activity on mental functions and behavior. It is ironic that biological research on the anatomy of the brain began in earnest soon after Descartes' distinction between the mind and the body became widely accepted (Zimmer, 2004). By the late-nineteenth century, it was known that physical processes in the brain were, in some manner, important for mental processes. In fact, specific structures in the brain had been linked to specific mental functions such as language and perception. By 1890, research on the nervous system had led to the emergence of a neurological approach to the study of the conscious mind — an approach that assumed that conscious mental processes were associated with, and perhaps caused by, physical processes occurring within the brain. As implied in this definition, the conscious mind was thought by some psychologists and biologists to be fully explainable by natural processes (the physical processes occurring within the nervous system) and, hence, to be a part of nature. Other psychologists and biologists, however, believed that, even if the mind and brain are tightly linked in some mysterious way, the mind still was a supernatural entity that was part of the human soul.

[METHODOLOGICAL & METAPHYSICAL NATURALISM WILL BE DISCUSSED IN CLASS.]

Study Questions 1-1

17. In the late-nineteenth century, which two disciplines had the biggest influence on the topics studied by experimental psychologists and the methods used to study them?
18. What were early experimental psychologists most interested in studying scientifically?
19. What is meant by the term "detachable soul" and what influence did this concept have on views of the mind?
20. How would you describe in your own words Rene Descartes' concept of mind-body dualism?
21. What led Descartes to conclude that animals have no free will?
22. How would you describe in your own words the doctrine of determinism?
23. What influence did Descartes' concept of mind-body dualism have on the development of scientific psychology?
24. What is the neurological approach to the study of the mind?
25. In the late-nineteenth century, what were two views about the nature of the mind-brain link among those adopting a neurological approach to the study of the mind?

What is the Brain-Mind Theory?

Beginning around 1890, the claim that all human cognitions, emotions, and behaviors are caused directly by activity of the nervous system gradually became the dominant view in the field called biological psychology. We will refer to this claim as the brain-mind theory. A theory is a causal explanation of a phenomenon that is based on supporting evidence[∂]. For example, a child watching the sun move from the eastern horizon to the western horizon during the day might wonder about the cause of the sun's movement. There are two alternative theories that can explain the movement:

• Theory 1: The sun makes one complete revolution around the earth every 24 hours.
• Theory 2: The earth makes one complete rotation on its axis every 24 hours.

Theory 2 implies that the sun only appears to be moving, whereas Theory 1 states that the sun actually is moving. In deciding which theory was more likely to be true, ancient researchers needed to collect evidence and determine which theory was better supported by this evidence. You will learn more about theories and how best to test them in Section 1-2 and in the remainder of the book. For now, you need only to remember that a theory is a causal explanation of an event or set of events — an explanation that either is or is not supported by evidence.

Some of the evidence for the brain-mind theory comes from the specific impairments in mental functioning and behavior experienced by people who have suffered damage to specific areas of their brains. The neurologist, Oliver Sacks (1995), described a man who had a large part of his brain destroyed by a benign[∂] tumor. While the tumor was growing and after its removal in 1975, this man — to whom Sacks gave the pseudonym[∂], “Greg” — exhibited many problems often seen in others who have experienced brain damage in the same area. For example, Greg became blind and obese, lost all his hair, and often made bizarre comments. Furthermore, he did not seem to know where he was or what the date was. In fact, he believed that he was living in the late 1960s — a time period during which he had been a teenager. During that time, he had been heavily involved in the "hippie culture," taking drugs and eventually devoting himself to the practice of an Eastern religion. Sacks first met Greg in 1977:

Lacking facial hair, and childlike in manner, he seemed younger than his twenty-five years. He was fat, Buddha-like, with a vacant, bland face, his blind eyes roving at random in their orbits, while he sat motionless in his wheelchair. If he lacked spontaneity and initiated no exchanges, he responded promptly and appropriately when I spoke to him, though odd words would sometimes catch his fancy and give rise to associative tangents or snatches of song and rhyme. Between questions, if the time was not filled, there tended to be a deepening silence; though if this lasted for more than a minute, he might fall into Hare Krishna chants or a soft muttering of mantras. (p. 45)

Greg's amnesia[∂] was so severe that he seemed to have forgotten much of what had happened to him from about 1968 and after; and he was unable to remember anything that had happened more than about 20 seconds before. Thus, Greg’s brain tumor and its removal caused severe and permanent impairments physically, behaviorally, and psychologically. These impairments were linked directly to the specific areas damaged by the tumor. These are the findings that one would expect if the brain-mind theory were true.

What is the Evolutionary Approach to the Human Mind?

From about 1780 to 1860, the gradual emergence of evolutionary views of human nature altered how scientists and philosophers thought about the human mind. Evolution refers to the change over generations of a characteristic in a population of organisms. For example, many species of bacteria have evolved resistances to the previously lethal effects of a number of antibiotic medications since they were first introduced during the 1940s. And the physical, mental, and behavioral characteristic of dogs have shown enormous evolutionary changes since the initial domestication of wolves, the ancestors of modern dogs, by humans over ten-thousand years ago.

It was not until the publication in 1859 of Charles Darwin's book, On the Origin of Species By Means of Natural Selection, that biologists and psychologists began to seriously develop evolutionary theories of the human mind. These attempts to apply evolutionary thinking to the emergence of the human mind, in combination with the discoveries of those studying the human brain, led to an even greater tendency among biologists and psychologists to view the human mind as part of nature and, hence, explainable (in principle) by natural processes. Darwin was at the forefront of this tendency: in his later writings, he argued that over many millions of years gradual changes occurred in the mental abilities of our primate[∂] and hominid[∂] ancestors — changes that led eventually to the evolution of the complex minds of modern-day humans.

According to Darwin's view, some of the same ancestors that gave rise to modern humans also gave rise to other modern primates, such as modern chimpanzees. Thus, if Darwin's claims about the evolution of the human mind are true, then our minds should share at least some similarities with the minds of closely related primates. In other words, Darwin argued that there exists a mental continuity between closely related animal species: the mental abilities of closely-related modern species should show similarities whenever those mental abilities first emerged in an ancestral species that they share. Thus, the concept of mental continuity suggests that, if we want to find evidence that a mental ability or behavior has evolved in humans, we should observe our primate relatives to determine if they share this characteristic, at least to some degree. For example, a number of researchers have studied language abilities in other primates, such as chimpanzees and gorillas. Some chimpanzees and gorillas have been taught to use nonspoken language, such as sign language. And, even though their language abilities are much less impressive than those of humans, the fact that they can learn words and then use them in novel combinations to effectively communicate with researchers suggest that the several areas within the human brain associated with our complex language abilities first emerged in a primate ancestor shared by chimps, gorillas, and humans.

The acceptance of the principle of mental continuity led many nineteenth-century behavioral scientists to study animals closely related to humans in the belief that the behaviors observed in these species would help us to understand the nature of the human mind. Scientific psychology emerged from this research activity:

The influence of Darwinism upon psychology during the last quarter of the nineteenth century probably did as much as any single factor to shape the science as it exists today. Psychology was certain to become consistently more biological; mental processes tended more and more to be stated in terms of the functions served in the task of adjusting to the world. ... As a natural consequence, interest in animal psychology rapidly increased. Many books appeared which concerned themselves with the nature of instincts and with the phylogenetic [that is, evolutionary] study of intelligence. Studies of animal behavior appeared in psychological journals. The great gulf established by Descartes between human and animal psychology had been bridged. The life of the organism was seen as a whole. Human psychology was to be seen in relation to all the phenomena of life. (Murphy, 1949; p. 116)

Thus, Darwin’s work brought human nature fully within the realm of scientific inquiry. After the 1859 publication of his most important book, On the Origin of Species, many came to believe that they could use the methods of science to resolve once and for all the various philosophical controversies that had brewed for centuries.

Study Questions 1-1

26. How would you define the word "theory" in your own words?
27. In our everyday lives, we are always developing theories to explain the world around us. What is an example of a theory that you have developed to explain something in your everyday life (such as why people run red lights more often in Arizona than in other states)?
28. What is the brain-mind theory?
29. What is some evidence supporting the brain-mind theory?
30. What does it mean to state that the brain-mind theory views the human mind as a part of nature?
31. What is meant by the term "evolution"?
32. How did the work of evolutionary biologists such as Charles Darwin change the way in which we viewed the human mind?
33. What is meant by the term "mental continuity"?
34. How have studies of mental continuity demonstrated that human mental functions, such as language, may have evolved?

Summing Up. The claim that brain activity causes all mental activity is very different from the dualistic claim made by Descartes, who argued that the body (brain) and the mind are different in their essences (one being of the natural world and the other being supernatural), and that only humans have a mind. The brain-mind theory in conjunction with evolutionary biology effectively eliminated the distinction between the mind and the body as well as that between humans and other animals. The human mind, according to this biological view, is caused by natural processes occurring within the nervous system — processes that have evolved from those of nonhuman ancestors. As the nervous system evolves, therefore, the mental processes and behaviors caused by its activity evolve along with it.

Today, most scientific psychologists assume that all behaviors and all mental events are caused by a multitude of factors and, therefore, they assume that the doctrine of determinism holds for human cognitions, emotions, and behaviors. Some even have argued that our feeling that we freely choose our behaviors is simply an illusion (Wegner, 2002). The issues are complex, however, and simple answers to ancient philosophical and religious question are not possible. What the discoveries of scientific psychology mean for the doctrine of free will and for our own place in the universe ultimately must be decided by each of us.