CHAPTER 1                            LESSON 3



Physiological Measures: Activities of Brain and Body



The assignment of an orderly system of numbers to behaviors or traits.































Galvanic skin response (GSR)

Electrical changes in the skin associated with the activity of the sweat glands.









         Psychologists are also interested in the measurement of any physiological characteristics that have a bearing on behavior. They have found, for example, that certain abnormal states such as severe depression may be triggered by disturbances in the chemistry of the brain. They have also shown that the feelings of hunger are not necessarily caused by activity of the stomach, as popularly believed, but by measurable changes in the composition of the bloodstream. They have also shown that the body may respond at times with changes in hormones that are related to anxiety, although the individual reports feeling no emotion.


         As described in the next chapter, new techniques now allow researchers to study the brain directly-its structure, blood flow, chemistry, and electrical activity-while the individual is engaged in a variety of activities or while experiencing unusual states of consciousness such as those produced by sleep, drugs, or hallucinations. Researchers have measured the activity of the glands that influence emotions, and the way the arousal of emotions produces changes in the heart rate, blood pressure, and breathing. They have measured muscle tension and brain wave activity in states of stress and relaxation. In identifying some of the chemicals, produced in nerve endings, that transmit nervous impulses, they have found how irregularities in these chemicals play a part in mood and behavior.


         Often it turns out to be important to use physiological measures in conjunction with other methods since they may reveal information otherwise unavailable. For example, individuals suffering certain brain injuries have reported being unable to recognize familiar persons in photographs. However, when electrodes are placed on their palms to measure the galvanic skin response (GSR)-that is, the electrical changes associated with sweating-it is clear that the photographs of familiar persons do indeed arouse a response (Tranel & Damasio, 1985). This means that at some deep, unconscious level, recognition is taking place.




Measuring the Differences Among Us


Individual differences Variations between members of the same species.






A branch of mathematics that analyzes and summarizes data and then draws conclusions from that data.












Normal curve of distribution

A bell-shaped curve illustrating that for many events in nature most cases cluster around the average and decline near either extreme.



          Psychology's methods have been particularly helpful in adding to our knowledge of individual differences among people. Every person is indeed unique, and physical and psychological traits, from height and muscular strength to intelligence and emotional sensitivity, vary over a wide range.


    In studying individual differences, the science relies heavily on mathematical techniques known as statistics.  Many human traits, from height and weight to intelligence, fall into a similar pattern. Regarding height, for example, the measurements for adult American men range all the way from around 3 feet to around 8 feet. But most cluster around the average, which is now about 5 feet 9 inches, and the number found at each point in the range goes down steadily with each inch up or down from the average. Note the graph below, which shows how IQs as measured by intelligence tests range from below 40 to above 160-but with the majority falling close to the average of 100, and only a very few at the extreme low or high levels.


  The pattern shown in below is so typical of the results generally found in all tests and measurements that it is known as the normal curve of distribution. The message of the curve is that in many measurable traits, physical and psychological, most people are average or close to it, some are a fair distance above or below, and a few are very far above or below. Those who are about average have a lot of company. Those who are far removed from the average-in intelligence the geniuses and the mentally retarded, in height the seven-footers and the four-footers-are rare.


         The curve of normal distribution helps explain a great deal about behavior, including the general similarities displayed by most people and the wide deviations shown by a few others. The curve applies to performance in school. (Most students have to do an average amount of struggling; some can make A's without turning a hair; some cannot handle the work at all.) It applies to musical talent, athletic skill, and interest or lack of interest in sex- as well as to the intensity of emotional arousal and the strength of motives for achievement, power, and friendship. These and many other individual differences are the reason you cannot generalize about humanity as a whole from your own traits--especially on a matter in which you happen to fall at an unusually low or high point on the curve.







Individual differences in IQ The graph was obtained by testing the IQs of a large number of people in the United States. Note how many people scored right around the average of 100. (A total of 46.5 percent showed IQs between 90 and 109.) Note also how the number falls off rapidly from the midpoint to the lower and

upper extremes. Fewer than 1 percent of all people showed IQs under 60 and only 1.33 percent were at 140 or over (Terman & Merrill, 1937).



Correlation: To What Extent Is "A" Related to "8"?






























A statistical method examining the
relationship between two measures.


         Consider a question that has interested psychologists almost from the beginning of the science: Do children resemble their parents in intelligence? This question has many implications for study of the part played by heredity and environment-which, as you will see a little later, is one of the basic issues in psychology. How would you try to go about answering it?


    A person untrained in the methods of science might jump to conclusions based on personal experience: "No, obviously not. My neighbors the Smiths are both smart people-they went to college and have good jobs-but their two kids are having a terrible time in school." Or, "Certainly. My neighbors the Joneses are geniuses and their two daughters are the smartest kids in their school."


  A more sophisticated approach would be to look at a much larger sample of children and parents than provided by just the Smiths or the Joneses-and give both generations intelligence tests rather than to rely on personal impressions of how smart they seemed to be. This would be a good start toward a scientific answer. But the results would be difficult to interpret, because the tests would show contradictions. One mother and father, both with IQs of 120, turn out to have an only child whose IQ is also 120-but another couple with the same IQ has an only child with an IQ of 90. One mother at 95 and father at 85 have an only child with an IQ of 90-but a similar couple has a child whose IQ is 125. Even in the same family the tests would sometimes show three children with IQs as far apart as 85, 115, and 135. Without some method of analyzing and interpreting the test results, any scientific answer to the question would still be elusive.


  In this type of situation, psychologists apply a statistical tool called correlation. This is a mathematical method used to examine two different measurements (such as the IQs of parents and the IQs of their children)-and to determine what relationship, if any, actually exists between the two. The method, computes a coefficient of correlation ranging from 0.00 (no relationship at all) to 1.00 (a one-to-one or absolutely perfect relationship.) In the case of parents and children, the coefficient of correlation between IQs has generally been found to be about 0.50-indicating a fairly high, though by no means perfect, relationship.



You will find many correlations mentioned throughout this course, but a word of caution is in order. Correlations reveal the existence and extent of relationships, but they do not necessarily indicate cause and effect. Unless they are carefully interpreted, correlations can be misleading. There is a high correlation between the number of permanent teeth in children and their ability to answer increasingly difficult questions on intelligence tests. But this does not mean that having more teeth causes increased mental ability. The correlation is high because increasing age accounts for both the new teeth and the mental development. Usually when two traits are correlated it is because a third process is the cause of both of them.




These are vocabulary definitions that you need to be familiar with the chapter test.  In your notebook, write the term after the given term.


1.   Psychology is defined to be the systematic study of behavior and mental processes-including thought and emotion-and the factors that influence them. The term "systematic study;' meaning the use of rigorous and highly disciplined methods of science rather than relying on judgments based on insufficient evidence or unwarranted generalities, distinguishes ________  from the views of behavior proposed in philosophy and literature.

2. Psychology studies our physical activities-everything we do from the time we wake up in the morning until we go back to bed and fall asleep. All these forms of activities are the  _______ that the science of psychology studies.

3. Psychologists also study the activities that take place inside of us-the ways we learn, remember, forget, feel hungry, become angry or joyful. Such,  __________  __________ , which include  __________ and _______, are also embraced by the study of psychology.

4. In addition, psychology studies the things and events that influence behavior and mental processes, including the human brain, sense organs, chemicals in the bloodstream, heredity, the actions of other people, and so forth. These  _______  that influence behavior and mental processes are a third category of items studied by psychologists.


5. Psychology, then, is the __________ __________ of ____________ and __________  _________

-including ________ and ________ and ___________that influence them.


6. The missions of psychology are (1) to understand behavior and mental processes and (2) to predict their course. For example, psychologists try to ________  why individuals behave as they do in a classroom or in social situations to ___________  how they would behave in school or in a social environment.


7. The missions of psychology, similar to the goals of all sciences, are to _______ behavior and mental processes and to __________  their course.


8. Psychology is one member of a family of sciences often referred to as the behavioral and social sciences. Subject matter ranging from the neurochemical basis of memory and mental illness to the dynamics of global commerce and international conflict constitute the domain of the ____________  and  ________ _______.


9. Scientists who study genetics, physiology, anthropology, economics, linguistics, education, sociology,  and political science are all members of the _________ and _______ __________and those who study behavior and mental processes in particular are part of the field of __________.


                CHECK ANSWERS