An Introduction to Psychology:
The Science of Mind and Behavior

What Is Consciousness?

When we say that we are "conscious," we mean that we are aware of "something." Is there ever a time in our lives when we are not aware of "something"? Perhaps when we are in a deep coma; perhaps when we faint; and perhaps when we experience any other neurological condition in which the average level of brain activity is very low, especially the average level of activity in the cerebral cortex: the outer layer of the brain that is associated with many of the "higher" mental functions of humans and other animals (see Section 2).

But most of the time, it seems, we are conscious of "something." Even when we sleep, we are conscious of mental events, such as dreams (although we may not remember them when we wake up). Furthermore, we are aware of noises, smells, tastes, and touches coming from the environment around us. Sometimes, we incorporate them into our dreams (for example, dreaming about a police siren when we hear a dog howling next door) or they wake us up (for example, being awakened by a newborn baby's whimpering or an alarm clock). On the other hand, there are many mental events of which we are unaware, such as the mental processes involved in producing rapid and highly coordinated habitual movements (for example, typing on a computer keyboard). In order to explain why we so often are unaware of what is going on in our own minds, nineteenth-century philosophers, psychologists, and "medical psychologists" (later called "psychiatrists") distinguished three levels of awareness: the conscious, preconscious, and unconscious levels.

The Conscious Level
The conscious level of awareness contains cognitions and emotions to which one currently is attending. For example, right now, you probably are aware of the words you are reading and perhaps one or two other things going on around you (such as sounds coming from the next room or an itch on your back). But your attention is constantly shifting, so that what is in your awareness is always changing. For example, teachers often repeat important points several times because they realize that, at any one time, many students' attention is focused elsewhere. It is virtually impossible to keep one's attention focused on a single thing for an extended period of time. People with various mental disorders — such as anxiety disorders, mood disorders, psychotic disorders, and attention-deficit disorder — find this to be much more difficult than others.

The Preconscious Level
The preconscious level of awareness contains cognitions and emotions to which one currently is not attending, but could easily do so. For example, your memory of what you had for breakfast this morning is probably at the preconscious level. You can easily shift your attention to this memory and recall what you ate (or didn't eat). Or the set of tactile (touch) sensations involving your left big toe are probably at the preconscious level until you shift your attention to them, thereby bringing them to the conscious level. Attention, therefore, may be thought of as the mental process that transfers information from the preconscious and unconscious levels of awareness to the conscious level. In the case of information at the preconscious level, attention is easily able to bring the information into consciousness. The matter is very different for the unconscious level.

The Unconscious Level
The unconscious level of awareness contains cognitions and emotions to which it is very difficult or impossible for one to attend. For example, when you have a word on the “tip of your tongue,” you feel as if the word exists somewhere in your mind, but you simply cannot get to it. You may even remember the first letter and the number of syllables, but the rest of the word remains outside the reach of your attention. Nevertheless, you may find that, eventually, the word "pops" into your consciousness, even when you no longer were trying to remember it. This means that unconscious cognitive processes, in some unknown manner, were "searching" for the word the entire time; and, when it finally was "found," brought it to consciousness.

In general, we can think of the three levels of awareness as existing on a continuum, with mental content and mental processes currently within awareness at one end of the continuum, and mental content and mental processes that could never be brought into awareness at the other end:

Figure 1. The Levels of Awareness & the Ease or Difficulty
of Attending to Mental Content at Each Level.

We are constantly processing events around us at the preconscious and unconscious levels. This can be demonstrated by considering a common experience that has been dubbed the cocktail-party phenomenon (Moray, 1959). When you are at a party speaking with someone, your attention generally is focused on that conversation, not on the conversations among others around you. Nevertheless, if something important is occurs in one of these other conversations — for example, someone mentions your name followed by raucous laughter — it is very likely that you will shift your attention to that conversation. This shows that, although you were not consciously aware of what was being said in the other conversation, there were preconscious or unconscious mental processes analyzing the information and causing attention to be directed to it when something important occurred.

Another way to think of attention and awareness is to think of the mind as analogous to a large but unlighted warehouse, and of attention as a flashlight that is anchored somewhere in the middle of the warehouse. The flashlight is able to shine a very bright but narrow beam of light wherever it is pointed (see Figure 2). The farther from the middle of the warehouse is an object, the more difficult it is to see with the flashlight. Objects in the corners and against the outer walls are impossible to see (the unconscious level).

Figure 2. The Mind is Represented As a Rectangle and Attention (the Conscious Level) as the Yellow Circle. Attention Can Move Around Easily in the Light-Blue Portion (the Preconscious Level) But Not in the Dark-Blue Portion (the Unconscious Level).

What is an Altered State of Consciousness?

As anyone who has consumed too much alcohol already knows, the characteristics of the conscious level can change during the waking state. When intoxicated, people tend to show reductions in their ability to inhibit behaviors, evaluate situations, focus attention, and make rational decisions. When intoxicated, people are in an altered state of consciousness (that is, an altered state of the conscious level of awareness), which may be defined as a condition of the conscious level in which there are significant changes (from the normal waking state) in cognitive and behavioral functioning — changes that include, but are not limited to, the following:

• the mental processing of information becomes shallow and uncritical;
• self-perceptions and perceptions of the environment become distorted;
• self-control and normal inhibitions diminish, and may even disappear.

It is important to remember that, when we speak of an altered state of consciousness, we are referring only to what is going on at the conscious level: the characteristics of the preconscious and unconscious levels of awareness are not being described or investigated.

Sleep is an altered state of consciousness that we experience every day. When we sleep, our consciousness is unable to engage in complex processing of information, it no longer has the ability to perceive the self or the environment accurately, and it no longer is able to exhibit self-control or to inhibit behaviors, emotions, and cognitions, because there exists no awareness of our physical selves (that is, we do not perceive ourselves as a person lying in bed sleeping and dreaming). Thus, during sleep, the characteristics of the conscious level of awareness have undergone significant changes from the normal waking state.

Study Questions

1. How do the conscious and preconscious levels differ? How are they similar?
2. How do the conscious and unconscious levels differ? How are they similar?
3. How do the preconscious and unconscious levels differ? How are they similar?
4. How is the mental process of attention related to the three levels of awareness?
5. What is an example of the cocktail-party phenomenon from your own life? (Note: The example does not need to have happened at a party.)
6. How would you define in your own words the concept of "altered stat of consciousness"?
7. What are some examples of significant changes in the three types of functioning listed above when people are in the altered state of sleep associated with sleepwalking?
8. How are levels of awareness similar to altered states of consciousness?
9. How do levels of awareness differ from altered states of consciousness?

How Should Psychological Concepts Be Defined?

In defining what is meant by levels of awareness and an altered state of consciousness, we begin to dee how important and difficult it is to define psychological concepts in ways that make sense and that can be used in designing research studies. In general, the way in which a concept is defined is very important because the definition determines how we think about the concept as well as the actions we take with respect to it. For example, the way in which medical doctors define the concept of death will influence at which point they stop trying to resuscitate[∂] a person. An important difficulty for defining psychological concepts is that many of them are used in everyday life, which often causes them to have multiple meanings. For example, there are at least two meanings of the concept of "unconscious" in everyday life:

(1) When we say that "Stephanie has repressed the memory of her car accident," we mean that she is unaware of a cognition that actually exists "somewhere" in her mind. In this case, the term "unconscious" refers to a level of awareness within the individual's mind. Mental content in the unconscious level is either very difficult or impossible to attend to.

(2) When we say that "Stephen is unconscious," we mean that he shows no awareness of the external world around him, such as when he is asleep. In fact, we show only reduced awareness of the external world while we sleep; if we weren't aware to some degree of the world around us, alarm clocks wouldn't wake us up. In this case, the term unconscious refers to an altered state of consciousness (the conscious level): the person is aware mostly of internal cognitions and emotions, but relatively unaware of sensory information coming from the outside world.

Because of the fact that many psychological concepts have multiple meanings, psychological researchers must carefully define their concepts. There are two general types of definitions used by researchers: subjective definitions and objective definitions.

Subjective Definitions
In everyday life, as well as in many therapeutic situations, people typically define concepts in an intuitive manner that is strongly influenced by personal biases, preferences, attitudes, etc. A subjective definition involves defining a concept in an intuitive manner based on general impressions — impressions influenced not only by reality but also by how one interprets reality (which allows personal biases, attitudes, etc., to affect relevant observations). For example, Potter Stewart, an Associate Justice of the United States Supreme Court from 1958-1981, provided a subjective definition of obscenity (pronography) in a 1964 ruling. A French film, Les Amants (The Lovers), had been banned from being shown in Ohio theaters because of an obscenity law that was in effect in that state. Nico Jacobellis, a manager of a theater outside of Cleveland, decided to show the film anyways. He was arrested and convicted. His case eventually made it to the Supreme Court, which ruled that the law had been incorrectly and unconstitutionally applied to the film. In his contribution to the majority decision, Stewart stated:

I have reached the conclusion ... that under the First and Fourteenth Amendments[,] criminal laws in this area are constitutionally limited to hard-core pornography. I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know [hard-core pornography] when I see it, and the motion picture involved in this case is not that. (JACOBELLIS v. OHIO, 378 U.S. 184, 1964; emphasis added)

Stewart admitted in his decision that he was defining the concept of "hard-core pornography" in an impressionistic and subjective manner; but his statement also seemed to imply that most people probably have the same subjective understanding of pornography as he, and that most therefore would agree with him when evaluating specific examples, just as we all can agree on which objects are red without being able to define precisely and objectively what "red" is. On this point, Stewart very likely was wrong: our standards of conduct and our moral values, which differ widely among individuals, determine whether or not we think of something as "obscene." Stewart himself eventually realized this and changed his mind on the matter.

Subjective definitions and suggestion. The more subjective is the definition of a concept, the greater becomes the influence of "suggestion" on observations. Suggestion is the automatic acceptance by an individual of an idea, who then acts on the idea with little or no critical reflection. In other words, what people say to you (or what they simply imply by their actions) can influence how you interpret your experience of an event or situation; and, thereby, what you do in response to it. In most cases, this influence occurs without any awareness: that is, it occurs at either the preconscious or (more often) unconscious levels. In general, suggestion affects what we believe about an event or situation, and our beliefs about an event or situation influence what we perceive when observing that event or situation.

A famous scientific example of the influence of suggestion on observations occurred at the beginning of the twentieth century. In 1903, soon after the discovery of X-rays — a previously unknown type of electromagnetic radiation that was invisible to the human eye — an eminent French physicist by the name of René Blondlot discovered what he called "N-rays" (named after the University of Nancy, which was where he worked). According to Blondlot and his colleagues, N-rays affect the perceived brightness of objects. For example, Blondlot claimed that N-rays increase the perceived brightness of electric sparks. Research supported his claim that N-rays are emitted from the sun, flames, and other glowing objects. In addition, according to these findings, certain substances, such as the vitreous[∂] fluid within the eye, absorb N-rays and then emit them later. This meant that, after N-rays are beamed into their eyes, they become better able to see in darkened rooms. Most of Blondlot's claims were supported by dozens of studies performed in different laboratories. Thus, it seemed certain to many physicists that Blondlot had found something very important.

Nevertheless, there are always skeptics; and a number of physicists doubted the evidence presented for the existence of N-rays. They doubted the evidence because they were unable to replicate these findings in their own laboratories. Furthermore, in explaining their failures to replicate, they pointed to a basic problem in the initial research: in all these studies, the researchers judged by sight (that is, subjectively) whether or not the brightness of an object supposedly being bombarded with N-rays had increased. These skeptical physicists argued that the suggestion that N-rays were aimed at the object being observed affected the researchers' perceptions of the object's brightness.

How could we test the claim that suggestion affected the perceived brightness of objects in these studies? We would need to use deception: we would need to make observers believe incorrectly that N-rays either were being beamed at an object when they were not or not being beamed at the object when they were, and then ask for their observations (see Table 1).

If the presence or absence of N-rays is the primary influence on what observers perceive, then Cell A and Cell C will contain the greatest number of instances in which the observers stated that the object appeared brighter to them; and Cell B and Cell D will contain the greatest number of instances in which the observers stated that the brightness of the object didn't change. On the other hand, if suggestion is the primary influence on what observers perceive, then Cell A and Cell B will contain the greatest number of instances in which the observers stated that the object appeared brighter to them; and Cell C and Cell D will contain the greatest number of instances in which the observers stated that the brightness of the object didn't change.

An American physicist by the name of Robert Wood performed this study in Blondlot’s laboratory in 1904:

N-ray experiments had to be carried out in a darkened laboratory.... This gave Wood an opportunity to make several observations that proved Blondlot’s judgements of brightness changes were a function of his beliefs [suggestion], and not of the presence or absence of N-rays. In one experiment, Wood was to block an N-ray source by inserting a sheet of lead between the source and a card with luminous paint on it [Blondlot had "discovered" that N-rays could not penetrate lead].... Without telling Blondlot, Wood changed the experiment in one slight but vitally important way. He would indicate to Blondlot that the lead sheet was blocking the N-ray source when it really wasn’t, or vice versa.... [Wood found that if Blondlot] believed the screen was present (blocking N-rays), but it wasn’t, he reported the paint to be less luminous. If he was told the screen was not present (allowing N-rays to pass), but it really was, he reported the paint to be more luminous. (Hines, 2003, p. 10). CHECK PAGE NUMBER

Thus, it was the observers’ beliefs about what was happening, not what actually was happening, that was the primary influence on their judgements of brightness. Further manipulations performed by Wood, similar in form to this one, provided no evidence to support the existence of N-rays. Hence, Wood concluded that the all the previous evidence that seemed to support the positive claims made about N-rays actually were contaminated by the effects of suggestion.

What is most interesting about this story is that Blondlot never gave up his belief in the existence of N-rays: “convinced until the end that N-rays were real, [Blondlot] pursued his research on the topic until his death in 1930” (Hines, 2003, p. 11 CHECK PAGE #). Personal experience (subjectively defined observations) — in Blondlot's case, his perceptions of an increase in the brightness of objects under certain conditions — is very compelling evidence for us, even when objectively defined observations (see below) provide incontrovertible[∂] evidence in support of a different conclusion. Belief perseverance refers to the strong human tendency to continue to hold a belief and to refuse to question it once the belief has been accepted as likely to be true. In other words, once people have developed a belief, they tend to ignore any argument that provides sufficient evidence for rejecting the truth of the belief or to resist its impartial evaluation. We all hold such “delusional” beliefs, partly because we don’t always realize how we might be led astray by inaccurate personal experiences. That is why there is no substitute for research studies that control for common problems in our everyday observations of the world. When faced with evidence from such research — evidence that contradicts our personal experience — we must be prepared to question and, perhaps, reject our beliefs.

Study Questions

10. What are the two meanings of "unconscious" used in everyday life?
11. In what way are we defining "unconscious" in this course?
12. How would you define "subjective definition" in your own words?
13. What is an example of a subjectively defined concept from your everyday life?
14. How would you define in your own words the concept of "suggestion"?
15. What is an example from your everyday life of an experience you had with suggestion?
16. How can a suggestion influence what you perceive?
17. In what way are subjective definitions and suggestion associated?
18. What did the evidence for the existence of N-rays consist of?
19. What was the main problem with this evidence; and how did the notion of "subjective definitions" enter into this?
20. How was the evidence supporting the existence of N-rays shown to be inadequate?
21. Have N-rays been proved not to exist? Why or why not? (The answer to this question was not provided above. If you are unsure of how to answer it, ask in class.)

Objective Definitions
A fundamental precept of science is empiricism: scientists must make direct observations that can either confirm or disconfirm a claim. Because subjective definitions of the concepts contained within claims have problems that do not allow us to make observations that convincingly confirm or disconfirm the claims (see above), scientific researchers must define their concepts objectively. An objective definition involves defining a concept in terms of a specific set of observations that can be verified by any competent observer. An observation that is verifiable is one that others are able to test in order to determine its accuracy. For example, we may objectively define the concept of a hot classroom as any classroom in which the temperature, as measured by a standard room thermometer, is at least 78º F (25º C). Or we may objectively define the concept of superior intelligence as any score on the Stanford-Binet Intelligence Scale of 116 or higher. In this course, the instructor has objectively defined an A, B, C, D, and F (see the syllabus). That is, he doesn't rely on his subjective impressions of how much a particular student has learned when assigning a grade to that student; the grade assigned (the observation made) depends entirely on the scores received on tests and assignments, with those scores being weighted according to a particular formula. Any competent observer should be able to test the accuracy of the observation (the grade assigned) by obtaining the student's scores and placing them into the formula.

As you can see from these examples, objective definitions differ radically from subjective definitions. Observations based on objective definitions are not based on arbitrary factors limited to the individuals making the observations — factors such as personal feelings, whims, or uninformed opinions. Furthermore, objective definitions also differ from dictionary definitions. A dictionary definition consists of a general statement made about the meaning of a concept, whereas an objective definition specifies a set of directly observable (measurable) events that give meaning to a concept — events that ideally can be measured with precision. For example, the dictionary definition of empathy is, "the ability to share in another person's emotions or feelings" (see Webster's New World Dictionary, 2nd College Edition). This definition, however, does not indicate how we would measure the average degree of empathy in individuals. An objective definition of empathy, on the other hand, must indicate how to measure this concept. For example, we might objectively define empathy in infants as "the amount of time it takes to begin crying while listening to an audio-recording of another infant crying."

As you probably now can see, objective definitions are essential for the ability of scientific researchers to empirically test claims. This is because objective definitions have two major advantages:

• Conceptual Clarity. Researchers using the same objective definition must, by necessity, be studying the same concept. This becomes very important when researchers investigate complex and fuzzy concepts such as "intelligence."
• Verifiability. A verifiable observation (measurement) is one that can be chacked by others for its accuracy or truth. Concepts that are objectively defined are relatively easy to verify in this way.

Nevertheless, objective definitions also have an important disadvantage:

• Validity. A valid observation is one that accurately measures the degree to which individuals exhibit the characteristic indicated by the concept being investigated. For example, a valid measure of intelligence (an "IQ test") is one that accurately reflects the degree to which individuals exhibit the characteristic indicated by the concept of intelligence.
  • Objective definitions generally measure not only the concept being investigated, but also other concepts. For example, the concept of knowledge of the course material may be objectively defined as the combination of scores on six multiple-choice tests. Although this seems to be a straighforward way of measuring the concept, the operational definition also includes measurements of anything else that might affect test scores, such as test anxiety, verbal comprehension, reading rate, distractibility, and test wiseness (multiple-choice test strategies). Thus, one person may get a low score because he suffers from severe test anxiety. Another may get a low score because she was distracted by a student who kept tapping a pencil. A third person may get a low score because he is a slow reader and the test had a time limit.
  • Objective definitions often cannot measure all aspects of a psychological concept because these concepts tend to be complex: they refer to a broad range of cognitions, emotions, and behaviors. For example, we might objectively define shyness as the total amount of time that a person avoids eye contact in a conversation with another person. Although this objective definition measures an important aspect of shyness, it should be obvious that the concept is more complex than can be captured by this single objective definition.

In order to minimize these two validity problems, researchers typically use a variety of objective definitions when investigating a concept. Although each objective definition may measure only selected aspects of the concept (as well as concepts other than the one being studied), the various objective definitions in combination will tend to converge on the concept. For example, a teacher who wants to measure the amount of knowledge acquired by students in a course may use a variety of objective definitions: multiple-choice tests, essay tests, short quizzes, research papers, oral reports, class participation, reaction papers, and so on. Each objective definition has weaknesses; but, when considered together, they should give a good idea of how much each student has learned in the course.

Testable Claims
If a researcher is unable to develop an objective definition of one or more concepts included in a claim, then that claim is untestable. This is because, in order to test a claim, its concepts must be linked to observable and verifiable events. Most psychological concepts can, with some ingenuity, be objectively defined. Nevertheless, there are some concepts for which there simply are no objectively observable and verifiable events that can be linked to them without including subjective elements, such as values and preferences. For example, there probably are no objectively observable and value-free events that can be linked to the concepts of "evil" or "freedom." In general, any claim that includes a concept or concepts that cannot be be linked to objectively observable and verifiable events is not testable. We will see in later sections that this requirement has made it very difficult, if not impossible, to test important claims made by those adopting certain theoretical approaches, such as the psychoanalytic approach.

Study Questions

22. How would you define "objective definition" in your own words?
23. What is an example of an objectively defined concept from your everyday life?
24. What is an objective definition of "knowledge of the course material" other than the one mentioned above?
25. What characteristics might an objective definition of "bad eyesight " contain?
26. What are the advantages of using objective definitions in research?
27. What are the disadvantages of using objective definitions in research?
28. How can researchers reduce problems introduced by these disadvantages?
29. What is a testable psychological claim that you have learned in this course? What makes it a testable claim?
30. What is an untestable psychological claim that you have learned in this course? What makes it an untestable claim?

How Are Correlational Studies of the Brain Performed?

When performing research on altered states of consciousness, researchers often measure brain activity and correlate it with changes in the state of consciousness. In general, correlational studies allow researchers to link activity in particular brain structures with changes in particular mental and behavioral functions. For example, people who have had a stroke often develop localized brain damage: the disruption of blood flow to and from a location causes the death of brain cells at that point. The death of brain cells often correlates with disturbances of mental and behavioral functioning, such as difficulties with speaking, writing, reading, or understanding the speech of others.

In general, there are two types of correlational study used to locate brain areas associated with mental and behavioral functioning.

1. In a damaged brain, researchers correlate the amount and location of damage with the severity of mental and behavioral abnormalities. In order to use this method, we need to be able to see the structures of the nervous system. Autopsies are often performed after subjects die in order to find where the nervous system has been damaged. But there are also several techniques that allow us to get pictures of the nervous systems of living subjects. Although X-rays have often been used for this purpose, there are much better techniques now available — techniques that give much clearer pictures of the nervous system (such as magnetic resonance imaging, or MRI).
2. In an undamaged brain, researchers correlate the degree of abnormal neural[∂] activity with the severity of mental and behavioral abnormalities. The brain works because of biochemical activity in the billions of cells, called neurons, that make up the brain. These biochemical changes cause electrical activity in neurons. By studying people with mental or behavioral abnormalities, researchers look for abnormalities of biochemical or electrical activity in specific areas of their brains.

To measure brain activity, early sleep researchers (beginning in the 1930s) used a device called an electroencephalograph (EEG), which is an old (and somewhat crude) method for measuring changes in the electrical activity of neurons. The EEG is limited in two ways. First, it is able to measure the electrical activity only of those neurons in the upper layers of the cerebral cortex. Second, it is unable to measure the activity of single neurons: it measures the summed electrical activity of millions of neurons over time. Nevertheless, since about 1920, it has helped brain researchers to measure mental states and often is used to diagnose neurological disturbances in individuals. Right now, if you were hooked up to an EEG machine, you would exhibit a high level of electrical activity in your cortex. If you were in a coma, on the other hand, you would show a low level of electrical activity in your cortex. The electrical activity is transformed into wave patterns that, in the past, typically were traced onto rolling sheets of paper. These tracings were referred to as “brain waves.” Today, brain-wave patterns are analyzed by specialized computer programs and are viewed on computer monitors. Changes in a person's state of arousal — from being awake and alert to deeply asleep — are associated with changes in brain waves:

(1) Beta waves show that a person is actively attending to events and, therefore, is aware of what is happening around you.
(2) Alpha waves show that a person is awake but is not actively processing visual information. Alpha waves generally are observed when the person is relaxed and inattentive (such as in daydreaming).
(3) Theta waves are observed when a person has fallen into a light sleep — a stage of sleep from which he or she can be awakened easily.
(4) Delta waves are observed when a person has entered deep sleep — a stage of sleep from which he or she cannot be awakened easily.

The four brain-wave patterns are illustrated in Figure 1.

Figure 3. Some of the Brain Waves Commonly Measured in Sleep Research
(From Tortora & Grabowski, 1996, p. 414).

In the next section, we will begin to look more closely at what sleep researchers, beginning in the early 1950s, have discovered about sleep.

What is Sleep & Why Do We Do It?

What happens to you when you go to sleep? What happens, for example, in your mind? Do you stop thinking; do you simply think less; or do you perhaps just think differently? Do thoughts and emotions in unconscious parts of your mind enter more easily into consciousness? Is sleep somewhat like entering another plane of existence; or perhaps even like death? And why do we spend so much of our lives (a little over a third of it, on average) sleeping? Does it help us to survive longer? Does it help our minds to run more smoothly? Does it help us to conserve energy, or perhaps to create new energy? Can we do with less sleep and still function adequately? Can we perhaps train ourselves to do without sleep at all?

There are many, many questions we can ask about sleep. I think that you probably have asked yourself at least some of these questions and probably different ones as well. How can we begin to answer them? Should we consult psychics or others who we think might have special insight into this subject? Should we look at what philosophers or other thinkers have to say about the matter? It may be that these people could be of some help to us in trying to answer our questions. Perhaps a psychic might tell us that dreams are messages from a spiritual plane of existence, and that we should pay attention to them since these messages come from entities trying to help us. Perhaps a philosopher might tell us that dreams are expressions of basic issues that derive from our unconscious minds—issues about life, death, and the meaning of our existence.

These are extremely interesting claims about dreams. Nevertheless, you might wonder how to be certain that these people know what they are talking about. That is, if we are to be good skeptics, we need to ask the following question: what evidence do these people have for their claims about sleep and its purposes? Did they perhaps learn their claims from other authorities? Did they test their claims directly? In fact, some people say that they have obtained their information from supernatural sources. Should we trust such evidence? What I am asking you to do is answer the following question: what would be the best evidence for showing the truth or falsity of claims about sleep and dreams?

The discussion presented throughout Section 1has indicated the kinds of evidence preferred by scientific researchers. First, scientific researchers are empirical in their approach. Therefore, they would want to observe people while they slept and ask them about their dreams when they woke up. Second, they are skeptical. A person with a skeptical attitude believes that we should always closely examine the evidence supporting any claim to knowledge and that answers to a research questions are rarely final: new evidence may show that an answer was wrong. Therefore, our claims about sleep must have sufficient evidence to support them.

But, even accepting the scientific approach as our starting point, there is still a major problem. What exactly should psychologists observe in order to find out something important about sleep? Should they observe bodily movements during the night; changes in blood pressure and digestion; changes in heart rate; changes in brain activity; changes in what goes on in the mind of the sleeping person; or something else? Because there are so many phenomena one could observe, it is difficult to know where to start. It turns out that what we choose to observe depends upon what we think might be the important proximal or distal causes of the phenomenon we are studying. In other words, we must have an initial theory, even if it is a highly speculative one, about how best to explain the phenomenon we wish to study. For example, if you want to understand why your car isn’t working, what observations are you going to make? It depends upon what you believe to be the proximal cause(s) of the normal functioning of the car. If you believe that a car runs because of invisible elves living in the glove compartment who, when you turn the key, travel into the engine and make the parts move, then you’ll probably make detailed observations of the glove compartment to see if you can detect any problems with the invisible elves. We know, however, that the normal functioning of a car is caused by the combustion of fuel in your engine that then activates other parts in your engine. (It still might be that invisible elves do live in your glove compartment, but we don’t have to try to observe them to get the car running again). Therefore, you will make careful observations of the activity of different engine parts with regard to these combustive events.

In the case of sleep and dreams, researchers have most often observed the following events:

(a) the electrical activity of the brain during sleep;
(b) the bodily movements of people while they sleep;
(c) the physiological processes within the body during sleep;
(d) the mental experiences had by people while they sleep.

The reasons for observing people while they sleep and asking them what they have experienced during sleep are probably obvious to you — such observations are essential if we are going to understand anything about sleep. The reasons for observing the electrical activity of the brain also should now be obvious: electrical activity in the nervous system is the most proximal cause of cognitions, emotions, and behaviors. After deciding on what to observe and making the observations, a second problem arises: how should these observations be explained? The development of adequate theories generally is a much greater problem for the scientist than observing and describing the phenomenon itself. As for sleep, we will see that many different theories have been developed depending upon what researchers were trying to understand about sleep.

Changes in Brain Activity
In order to describe the changes that occur during sleep, two researchers at the University of Chicago — Eugene Aserinky (1921-1998) and Nathaniel Kleitman (1895-1999) — looked at changes in electrical activity in the brain with the EEG (Aserinsky & Kleitman, 1953). Before 1953, scientists trying to describe and understand sleep also realized that changes in brain activity must produce sleep: there were obvious changes in behavior and mental events that could be explained only by supposing that changed electrical activity in the brain was involved. However, not until Aserinsky and Kleitman came along did sleep researchers begin to have a more complete understanding of what was going on in the brain during sleep.

What do you think might happen to the brain’s activity during sleep? Well, since thinking seems to slow down and become more illogical during sleep, it seems reasonable to predict that, the longer we sleep, the less active the brain becomes, and that it becomes more active only when we begin to wake up again. Before beginning their own research on sleep, Aserinsky and Kleitman also believed that earlier research had already shown this to be true and, therefore, they decided that studying changes in brain activity during sleep would be unnecessary and unproductive. In testing the EEG machine before beginning his research, however, Aserinsky noticed that, several times during the night, the eyes of his subject (his eight-year-old son) moved about very rapidly, and that this movement was associated with increased brain activity. In fact, his son's brain became so active that it looked as if he was wide awake! Aserinsky and Kleitman had not expected this finding. It was sufficiently interesting that they began a research program to develop a better understanding of what was happening in these very active sleep periods. They soon referred to these periods as rapid-eye-movement (REM) sleep because of the rapid bursts of eye movements under the closed eyelids.

By measuring changes in brain activity during sleep and determining when particular brain waves were most likely to occur, Kleitman and his colleagues distinguished several stages of sleep. These stages were characterized by the average levels of brain activity observed. Furthermore, they noticed that there were many deviations from these averages, both within individuals from one night to the next, and across individuals on the same nights. Before discussing their findings further, we first need to better understand how we measure averages (means) and individual deviations from these averages (variances).

Study Questions

31. What are the two types of correlational study used to study the brain?
32. What is a neuron?
33. What is the EEG?
34. What are the major limitations of the EEG as a research tool?
35. What state of consciousness is a person in when he or she shows mostly:
    (a) beta waves?
    (b) alpha waves?
    (c) theta waves?
    (d) delta waves?
36. What did Aserinsky and Kleitman (1953) initially predict about changes in brain activity during sleep?
37. How did the observations made by Aserinsky and Kleitman (1953) show this prediction to be incorrect?

What are Means and Variances?

As discussed in Section 1-3, when two variables are correlated, this means that they change together, on average, in a large group of individuals. For example, major depression is correlated with sexual identity[∂]: compared to males, about twice as many females develop the disorder during their lives. In fact, Calvete and Cardeñoso (2005) summarized research demonstrating that this sex difference appears by adolescence:

[R]ecent research suggests that gender differences in psychological problems are evident during childhood and adolescence, prior to the acquisition of adult social roles. ... For instance, gender differences in depression begin to emerge at age 14 ..., and during the period from ages 15 to 18 the female rate of depression rises to double the prevalence rate for males. (p. 179)

When interpreting these results, there are two caveats[∂] of which we must be aware. First, the finding of this correlation tells us nothing about its cause, although we might begin to wonder if there is something about women (biologically, psychologically, socially, and/or culturally) that makes them more susceptible than are men to developing major depression. Second, finding that women are about twice as likely as men to develop major depression does not mean that a particular group of depressed people will have twice as many female members as male members. A group of depressed people will vary around the average ratio of two depressed females for every depressed male. Thus, when interpreting a correlation, we must be careful not to draw conclusions about the following:

• The nature of the causal relationship between the correlated variables. The directionality and third-variable problems limit what we can infer from a single correlation (see Section 1-3 ).
• The physical or psychological characteristics of individuals. Correlations represent what is true, on average, in a group of individuals. We cannot tell from an average what is true about particular individuals.

The Mean of a Sample of Observations
The average of a sample of observations typically is calculated as the mean, which is the summation of individual measurements divided by the number of measurements. For example, let's say that, in a class of ten students, the following test scores were obtained on a test with 100 questions: 70, 52, 90, 96, 46, 36, 78, 88, 66, and 98. Adding these ten score, we get 720. Dividing 720 by the number of scores (10), we get 72. Thus, the mean test score was 72: the "average person" in the class (who doesn't actually exist) answered 72% of the test questions correctly. Saying this another way, students had a tendency to receive a score of 72% (a C) on the test. Based on this information alone, however, a student cannot infer what his or her test score was. In fact, no student received a test score of 72% in the sample of ten students.

Nevertheless, many people with little or no training in research methods and statistics misunderstand and misinterpret the mean of a sample of observations. This becomes obvious when interpreting the results of research on social-group differences, such as studies of gender differences in psychological characteristics. For example, Bryan (1997) reported on research investigating gender differences among first-graders in their approach to solving arithmetic problems:

Results showed that by January of their first grade year, gender differences existed ... in the way that the children approached problem solving, not in the number of problems the students solved correctly. In both individual and group settings girls were more likely to use overt methods — counting on counters or counting on fingers — to solve the problems. Boys were more likely to use retrieval — relying on memorized answers — in both individual and group settings.

Over the course of the school year, boys were also more likely to increase their attempts to use retrieval even if they were not successful. Girls, however, seemed to be more concerned with being right and used backup strategies of counting on counters and counting on fingers. In group settings retrieval — the boys' preferred strategy — dominated the group work.

It is probable that many nonspecialists reading this report, especially those who show a strong reliance on gender stereotypes when thinking about gender differences, would conclude that boys approach math problems in one way and girls approach math problems in a very different way. But, as phrases such as "more likely" imply, gender-difference studies investigate differences between the means of a group of males and a group of females, not differences among individual males and individual females. Thus, finding that there is a difference between the means of a group of boys and a group of girls does not allow us to conclude that a particular boy or a particular girl has one or the other characteristic.

This point is easily understood by looking at an example of a gender difference in an easily observable physical characteristic, such as height. In October, 2004, the National Center for Health Statistics of the Centers for Disease Control and Prevention published a report (Ogden, Fryar, Carroll, & Fiegal, 2004) that included the average heights of Americans from 1960 to 2002 by age, race ethnicity, and sex. Table 2 shows the average heights (rounded to the nearest whole number) for non-hispanic white males and females between the ages of 20 and 39, inclusive, during the years 1999 to 2002 (for other groups and time periods, please see the report). The men are, on average, 5 inches taller than the women.

But the finding that, in this group, men are, on average, five inches taller than women obviously does not mean that a particular man selected from this group is five inches taller than a particular woman; or even that he is taller than the woman by any amount. Furthermore, these statistics tell us nothing specific about what the height will be of the next non-hispanic white man or woman between 20 and 39 years of age that we see. Although we can predict that the man probably will be closer to 70 inches than 65 inches, and that the woman probably will be closer to 65 inches than 70 inches, and that the man is likely to be taller than the woman, we will not know any of this for certain until we measure their heights. This is because, as can be seen in Figure 4, individual males and females vary around their respective means. The graph shows clearly that many women are taller than many men (indicated by the overlapping portion of the two distributions). In fact, some men are shorter than the mean height of women; and some women are taller than the mean height of men.

Figure 4. The Distribution of Heights in a Group of Non-Hispanic White
Americans Between the Ages of 20 and 39 Years (1999 to 2002).

The Variance of a Sample of Observations
Most individuals deviate to some extent from the means of their groups. The overall "spread" of measurements in a group generally is estimated by a statistic called the variance, which measures the degree to which individuals differ from the group mean (for a basic introduction to descriptive statistics[∂] such as the mean and variance, click on this link). The variance is important for understanding the average degree to which individuals differ from the mean. As you can see in Figure 4, the heights of individuals differ a great deal not only from the group mean, but also from each other. One very simple measure of variance is the difference between the lowest and highest scores — a measure called the range of scores. In the test-score example presented earlier, the lowest score was 36 and the highest score was 98, which gives a range of 62, which is a very large range. Most school tests that discriminate well between those who know the material and those who don't show a large range.

Because individuals typically differ from each other, even when they are drawn from a relatively homogeneous[∂] group, we must use statements such as the following when reporting on group averages and group differences:

• "there was a tendency for members of this group to..."
• "on average, members of this group will..."
• "individuals from this group were more likely than individuals from the other group to ..."

Nevertheless, people often misunderstand what the italicized words mean. For example, when the claim is made that men, on average, desire to have sex with more partners than women do, or that men are more sexually active, on average, than women are, some people conclude that, compared to all women, all men want more sexual partners or are more sexually active (in other words, that men "think" with their genitals). But such inferences do not follow from the finding of a difference between group means and, hence, are based on invalid and unsound reasoning. In this example, there is a significant number of men who show little or no sexual activity (either through masturbation or with partners) and a significant number of women who show a great deal of sexual activity (again, either through masturbation or with partners). The main danger of misinterpreting mean differences between groups is that it encourages stereotypical thinking — a topic that will be discussed later in this course.

What Do Differences Between Group Means Tell Us?

Students often ask psychology instructors about the cause(s) of a family member's or friend's mental disorder, such as bipolar disorder. The most accurate answer instructors can give to such questions is, "I don't know." But they then should discuss what research has shown to be possible or likely causes, such as the correlations that have been found between genes and bipolar disorder, the finding that stressful events often precede the first manic or depressive episodes, or the research that points to disturbances of biochemical activity in the brain. With these findings in mind, the instructor then might speculate that the person inherited genes that predisposed him or her to develop bipolar disorder; that a stressful event(s) probably triggered the development of the disorder; and that it probably would be beneficial for the person to try medications that reduce symptoms of bipolar disorder by changing biochemical activity in the brain. This answer is based on discoveries of average differences between groups or average associations between variables. Because averages can't be used to infer anything specific about an individual, the results of these studies don't allow the instructor to give a definitive answer to the question about the cause(s) of bipolar disorder in the relative or friend.

If averages tell us nothing definite about individuals, then why do psychologists spend so much time calculating them? Perhaps an example will help to answer this question. Let's say that we calculated the mean scores on the first PSY 101 test for two groups of students with different instructors, Dr. Smith and Dr. Jones, and obtained the following results:

Based on the mean scores, which instructor would you choose? Most of you probably chose Dr. Jones because his mean test score was higher. But, in doing this, you are ignoring the individual differences. Even though the average student received a lower test score in Dr. Smith's class, it may be that you would receive a much higher test score in her class, perhaps because her style of teaching meshes better with your style of learning.

Nevertheless, the difference in mean scores tells us that there is something about Dr. Smith's class that causes students, on average, to receive lower test scores. Because the study is correlational, however, we can't determine at this point what the important factor(s) is(are). It may be any one or more of the following:

• the time of day the class is held,
• the average intelligence of the students,
• the teaching style of Dr. Smith,
• the room in which the class is held,
• the average motivation of the students,
• the difficulty level of the test,
• the different textbooks used,
• the different material covered,
• the study aids provided,
• the day on which the test was given,
• and so on.

Thus, differences between group means help researchers to discover and test possible causal factors. Knowing that there is a difference between the average heights of men and women tells us that there is something associated with gender that determines height. Perhaps it has something to do with differing hormone levels, genes on the Y chromosome, etc. Researchers can test their causal hypotheses by controlling for the directionality problem, the third-variable problem, and extraneous variables, thereby eliminating alternative explanations. When experimental studies are discussed in Section 2, we will come back to the issue of controlling the research situation.

Study Questions

38. What are the two problems that limit what we can infer about cause-and-effect from the results of a correlational study?
39. The number of years of education is positively correlated with annual salary. What can you infer from this correlation?
40. What is the mean of the following set of IQ scores?
    95, 102, 99, 106, 93, 112, 105, 115, 80, 103,
    88, 98, 94, 110, 120, 97, 90, 101, 85, 107
41. What is the range of the set of IQ scores?
42. Did anyone in the group get the average IQ score for the group?
43. On average, young adults sleep an average of about eight hours per night. Given this finding, how much sleep should you get per night?
44. If you were trying to hire an accountant and had to decide between two equally qualified candidates, Tanya and Tony, whom should you hire given that males do better than females in math, on average?
45. On average, females have better verbal abilities than males. Who will get a lower grade in ENG 101: Peter or Patricia?
46. Research has shown that the following factors probably are causes of schizophrenia: genes, viral infections during fetal development, abnormal activity in the frontal lobes, damaged structures in the limbic system, birth complications, biological changes at puberty, abnormal activity in the temporal lobes, and stressful events that trigger the first psychotic episode. Amir has just developed symptoms of schizophrenia. What caused his schizophrenia?

In Section 1-5, you will learn about the characteristics of several stages of sleep. Keep in mind that what is being described there is accurate for the average young adult (people aged 20 to 40 years). You might find that you do not fit this average very well. Just as with height, it is to be expected that most people will deviate to varying extents from these averages (in psychology, a statistical deviation is simply a difference from some average). If you do deviate, this does not mean that you are abnormal in the sense that something is wrong with you. The very difficult issue of what constitutes a mental disorder will be dealt with in other sections of this course. If you become concerned about a problem you are experiencing with sleep, you always should talk with a professional before becoming too distressed over it.