Introduction to Psychology Individual Differences PDF

Introduction Most branches of psychology examine how people (or animals) behave in different settings or under different experimental conditions: they assume that people are all much the same. Thus when developmental psychologists talk about 'stages of development', the tacit assumption is that all...

Introduction Most branches of psychology examine how people (or animals) behave in different settings or under different experimental conditions: they assume that people are all much the same. Thus when developmental psychologists talk about 'stages of development', the tacit assumption is that all children develop in broadly similar ways. Likewise, social psychology produces theories to explain why people in general may show obedience to authority, prejudice and other group-related behaviours. Cognitive psychologists have shown that people recognise the meaning of a word more quickly when it is preceded by a semantically related 'prime'. Physiological psychologists often assume that everyone's nervous system has much the same sort of structure and will operate in much the same way. So much of psychology involves finding rules that describe how people in general behave. Yet this is only part of the story, for there is also significant variation between people. Some of this variation is random; people will behave differently on different occasions for reasons which are not clear. However some of the variations will be systematic. Some individuals are more obedient to authority or more prejudiced than others. Some people will recognise all types of words quickly while others will take far longer. Some will be more anxious than others, whatever the situation. The psychology of individual differences seeks to understand two things. It first explores the ways in which people vary psychologically -- using terms such as 'anxiety' or 'intelligence'. Second, it develops theories to explain how and why such variations in behaviour come about. Do these individual differences in anxiety or intelligence arise from the way in which children developed, their genetic makeup or the family environment which they experienced during childhood? Or are variations in physiological makeup, such as the extent and depth of the wrinkles on the surface of the brain or the amount of activity in the autonomic nervous system, linked to any of these characteristics? The possibilities are endless. Given that the aim of psychology is to describe, explain and predict the behaviour of organisms (people), it is clearly necessary to understand both the setting in which the behaviour occurs, the general laws and relevant individual differences. For example, in order to predict whether a jailed psychopath will re-offend if released, it is necessary to understand both the general law (the statistical probability that a jailed psychopath taken at random will re-offend), and individual differences that are related to re-offending behaviour (for example, the extent to which the person shows remorse or empathy for their victims). This book focuses on individual differences. I believe that there are four main reasons for studying individual differences: It is of interest in its own right. Most of us believe that personality, intelligence and so on are important characteristics of people when making friends and seeking partners -- perhaps enduring music which we dislike, boring parties and dating apps rather than simply marrying the person next door. But how should we conceptualise their personality? What characteristics of a person should we look for? Psychological tests are useful in applied psychology. The study of individual differences almost invariably leads to the publication of psychological tests. These measure abilities, knowledge, personality, mood and many other characteristics. They are of immense value to educational, occupational and clinical psychologists, teachers, nurses, careers counsellors and others who may want to diagnose learning difficulties, dyslexia or outstanding mental ability or seek to assess an individual's suitability for promotion, level of depression or suitability for a post that requires enormous attention to detail. The proper use of psychological tests can thus benefit both society and individuals. Tests are useful 'dependent variables' in other branches of psychology. Psychologists make extensive use of psychological tests when conducting experiments. A clinical psychologist may suspect that feelings of hopelessness often lead to suicide attempts. In order to test this hypothesis, it is obviously necessary to have some way of measuring hopelessness and by far the simplest way of doing so is to look for an appropriate psychological test. Cognitive psychologists studying the link between mood and memory ('state dependent memory') must be able to assess both mood and memory in order to be able to test whether a particular theory is valid and so they need sound mood questionnaires and tests or experimental tasks measuring memory. Other branches of psychology can predict behaviour better when they consider individual differences. Other branches of psychology rely on broad laws to predict behaviour, for example 'behaviour therapy', in which the principles of conditioning are used to break some undesirable habit. The therapist may know that a certain percentage of his or her patients may be 'cured' by this technique, but is unlikely to be able to predict whether any one individual is more or less likely than average to benefit from the therapy. However, it might well be found that the effectiveness of a particular type of treatment is affected by the individual's personality and/or ability -- a treatment that is successful in some individuals may be much less successful in others. By taking such individual differences into account, statistical tests become more sensitive. Instead of using analysis of variance to determine whether patients who are given behaviour therapy for a particular problem tend to show fewer symptoms than those who are assigned to a control condition, it is far better also to measure relevant personality and ability traits. One can then perform what is known as an 'analysis of covariance' instead. This shows whether the personality and ability traits are related to the number of symptoms shown and whether the two groups differ in the number of symptoms shown. It can show whether individual differences and/or the experimental condition influence behaviour. Main questions Any attempt to understand the nature of individual differences must really address two quite separate questions. The first concerns the nature of individual differences -- how individual differences should be conceptualised. There is a wide range of answers to this question, as will be seen in the following chapters. Indeed, it has been suggested that personality does not exist and that how we behave may be determined entirely by the situations in which we find ourselves rather than by anything 'inside us' and the evidence for such claims must be scrutinised carefully. The second important question concerns how and why individual differences in mood, motivation, ability and personality arise. It should be clear that research into the 'how' of individual differences can really only start once there is general agreement about their structure. It would be a waste of time to perform experiments in order to try to understand how 'sociability' (or 'creativity', 'depression', 'the drive for achievement', etc.) works if there is no good evidence that sociability is an important dimension of personality in the first place. Thus studies of processes must logically follow on from studies of structure. Process models of individual differences address questions such as the following. Why should some children perform much better than others at school? Why should some people be shy and others outgoing? Why do some individuals' moods swing wildly from depression to elation and back again? Why are some individuals apparently motivated by money to the exclusion of all else? We cannot hope to answer all of these questions in the following chapters, but we shall certainly explore what is known about the biological (and to some extent the social) processes that underlie personality, mood, ability and motivation. There is, however, one problem. Unless it is possible to measure individual differences accurately, it will be completely impossible either to determine the structure of personality, intelligence, etc. or to investigate its underlying processes. The development of good, accurate measures of individual differences (a branch of psychology known as psychometrics) is an absolutely vital step in developing and testing theories about the nature of individual differences and their underlying processes. For this reason, this book contains several chapters (3, 5, 8, 19--21) that focus on measurement issues. How can we discover individual differences? What sort of data should we use to discover individual differences? This is not an easy question to answer, for there are several possibilities. Clinical theories Several theories have grown out of the experiences of clinical psychologists, who realised that the ways in which they conceptualised 'abnormal behaviour' (particularly conditions such as anxiety, depression and perhaps schizophrenia) might also prove useful in understanding individual differences in the 'normal' population. Some have probably been rather quick to do this. Freud, for example, saw rather small samples of upper-middle-class Viennese women (many of whom showed symptoms that are so unusual that they do not appear in modern diagnostic manuals), refused to believe some of what they told him (such as memories of sexual abuse) and built up an enormous and complex theory about the personality structure and functions of humankind in general. Some clinically based theories are discussed in Chapter 2, and Freud's contribution is covered in Chapter 4. Studying individuals in detail Many people claim to have a rather good understanding of 'what makes others tick' -- for members of their families and close friends, at any rate. For example, we may believe that we know through experience how to calm down (or annoy) others to whom we are close and may feel that we have a good, intuitive understanding of the types of issue that are important to them, thereby allowing us to 'see the world from their point of view' and predict their behaviour. For example, we all have some intuitive feeling about when to mention difficult issues to those close to us. Perhaps getting to understand individuals in this way should be the mainstay of individual difference research? There are several difficulties with this approach, even if it can be proved that it leads to accurate prediction of behaviour. First, it will (presumably) take a long period of time to know anyone well enough to be able to make good predictions about their behaviour. Second, it is not particularly scientific, as it will be difficult to quantify anything, or say precisely how one intuits that the other person will behave. Third, the vagaries of language will make it very difficult to determine whether different people operate in different ways. Two people could describe the same characteristic in an individual in two quite different ways and it would be impossible to be sure that they were referring to precisely the same characteristic. However, the greatest problem of all is self-deception. It is very easy to overestimate how well one can predict someone else's behaviour and there is good evidence that most observers will see and remember the 1% of behaviours that were correctly predicted and ignore or explain away the 99% of predictions that were incorrect -- a phenomenon called 'confirmatory bias'. Davies (2003) discusses this in the context of personality assessment. Armchair speculation If one has made good, unbiased observations of how individuals behave in many situations, it might be reasonable to generate and test some hypotheses about behaviour. For example, you may notice that some individuals tend to be anxious and jumpy, worry, lose their temper more easily than most and so on. That is, the observer may notice that a whole bundle of characteristics seem to vary together and suggest that 'anxiety' (or something similar) might be an interesting aspect of personality. Of course, there are likely to be all sorts of problems associated with such casual observations. The observations may simply be wrong, or they may fail to take account of situations. For example, the people who were perceived as being anxious might all have been in some stressful situation -- it may be that the situation (rather than the person) determines how they react. Moreover, the ideas may be expressed so vaguely that they are impossible to test, as in Plato's observation that the mind is like a chariot drawn by four horses. Literature contains several testable hypotheses about personality, for example when Shakespeare speaks through Julius Caesar: Let me have men about me that are fat, Sleek-headed men and such as sleep o' nights, Yond' Cassius has a lean and hungry look. He thinks too much; such men are dangerous. (Shakespeare: Julius Caesar I:ii) This quotation suggests some rather interesting (and potentially empirically testable) process models of 'dangerousness'. Scientific assessment of individuals using mental tests Because of the problems inherent in other approaches discussed already, many psychologists opt for a more scientific approach to the study of personality and other forms of individual difference. One popular approach involves the use of statistical techniques to discover consistencies in behaviours across situations and to determine which behaviours tend to occur together in individuals. The raw data of such methods are either behaviours (such as performance on test items that require certain skills or knowledge), ratings of behaviour (obtained by trained raters who note well-defined behaviours and so very different from the clinical approach just mentioned) or self-ratings on questionnaires that are constructed using sound statistical techniques. Much care is taken to ensure that the measurements are both accurate and replicable. A major problem with this approach was flagged by Michell (1997). The problem is that most research in individual differences uses questionnaires or tests, as is discussed in Chapter 3 -- and Michell argues that the numbers which these tests produce do not constitute proper scientific measurement. A typical questionnaire item might be 'do you suffer from "nerves"?' and respondents are asked whether they strongly agree, agree, are neutral, disagree or strongly disagree with the statement. This item might be scored by awarding five points for 'strongly agree', down to one point for 'strongly disagree'; the higher the score on this item, the more neurotic the individual is thought to be. The problem is that these numbers do not behave the same way as measurements of length, weight, etc. For example, you should be concerned about whether someone who agrees with the item (scoring 4) is twice as neurotic as someone who disagrees (scoring 2). If you think that they are, remember that using numbers between 1 and 5 to represent the various responses was arbitrary; I could have chosen the numbers 0 to 4, in which case someone who agreed with the item (scoring 3) would have a score which is three times as large as someone who disagreed with it (scoring 1)... It is good to worry about such issues, because most psychologists -- even professionals and learned researchers -- do not, and tend to ignore Michell's work in the hope that it will somehow go away. We return to these issues in Chapter 3. Summary This brief chapter has introduced the general area of individual differences and has suggested that the topic is worth studying because of its inherent interest, the many practical applications of tests designed to measure individual differences, the need to measure individual differences in order to test theories in other branches of psychology and the ability to make more accurate predictions from theories that consider both individual differences and the impact of experimental interventions on behaviour. We have also considered some methods for studying individual differences, each with its own advantages and drawbacks, and have introduced the distinction between structural models ('how do people differ?') and process models which try to explain how these individual differences arise and operate.