Belbin 

Psychometrics involves the measurement and representation of psychological variables (such as intelligence, aptitude or personality type). It is heavily based on statistics and mathematical analysis. Measurement of individual differences is done using tests designed to be highly reliable (i.e. giving consistent results) and valid (i.e. measuring what they are supposed to measure). With respect to the study of personality, the psychometric perspective measures personality, describes personality structure, and often tries to explain the origins of personality in terms of biology, asking whether it is individual differences in biology that cause individual differences in personality. Although approaches such as humanistic psychology are also particularly interested in individual differences, the underlying philosophy of the two approaches is totally different, and form an interesting contrast. Humanistic psychologists attempt to take an 'idiographic' approach, that is try to understand a person in terms of their own, unique, worldview; this tradition also usually focuses on qualitative data, and takes a holistic view of people. Psychometrics, in contrast, will focus on quantitative data, using categories applicable to everyone, devised by the psychologist, into which the 'individual differences' of the person examined must fit. The focus is on aspects of people – particular dimensions of their behaviour and feelings; the concern is not with 'whole people' and their inner experience; the aim is to make statements about people in general. These are often based on 'personality traits': adjectives that describe enduring characterisics of people, used as the basic 'building blocks' of theories about personality. In attempting to measure personality, psychometrics focuses on the ways in which humans are like each other, in terms of their positions on broad dimensions, rather than with the ways in which each person is unique. The psychometric tradition has also typically seen human beings as having relatively fixed personality traits, in contrast to the humanistic emphasis on possibilities for self-directed change and transformation. Psychometrics has a long tradition in psychology, going back to Galton (around 1884) and is usually associated with biologically-based theories of evolution and heritability. This association led to (in modern terms) some rather ethically dubious connections between psychometrics at that time and movements such as eugenics, the desire to improve humanity through 'selective breeding'. In judging the viewpoints of earlier generations we perhaps do need to take into account the changing moral climate produced by changing socio-political contexts – e.g. eugenics, post-Hitler, probably has quite different connotations to those it would have had in the nineteenth century. As a tradition, psychometrics and individual differences psychology – whether in relation to personality, intelligence or other aspects of psychological measurement – has tended to develop and use its methods for practical applications as well as pure research. Psychometric instruments play an important role in occupational psychology, i.e. psychology applied to a work setting. The use of psychometrics to examine individual differences has been a crucial part of the growth of psychology as an empirical and scientific discipline. Over the last century, at first driven by education policies, and then recruitment into the military in the Second World War, increasingly sophisticated psychometric techniques have helped to develop a wide variety of psychological tests and led to a highly profitable industry. There are now many established tests of aptitude, intelligence and personality which are used both for research and in applied settings such as education, occupational testing for job selection, career counselling and in forensic psychology and clinical practice. 

Field research can take a wide variety of forms, but its essential characteristic is that it takes place in peoples' everyday social environments, as opposed to the artificial settings of a psychological laboratory (it is therefore seen as higher in 'ecological validity'). It can take the form of either observations (i.e. with no intervention by the researcher) or experiments (involving an intervention of some kind). Although cognitive psychologists have placed an increasing emphasis on doing research based on 'everyday life', i.e. in the field, field research is particularly valuable for social psychology. Although laboratory research can allow careful control of participants and the experimental setting, the special 'social context' of the laboratory itself can make it difficult to reliably generalize the results to human social behaviour in general. Field research can be qualitative or quantitative, or involve some combination of the two. 

Evolutionary. As the name suggests, evolutionary psychology tries to make sense of behaviours by looking at their possible evolutionary basis, i.e. how a particular behaviour might have helped humans adapt to their original prehistoric environments. This is an example of a functional explanation, as it seeks to understand a behaviour by seeing the possible function it may have played, within the evolutionary framework of Darwinian theory. The central idea is that modern humans will have brain structures, behaviours and motivations that evolved in prehistoric times but still exist today as genetically-transmitted, biologically based predispositions, passed down because of their adaptive value. A key point to understand is that evolutionary adaption (at least for humans) acts on long timescales, typically over tens or hundreds of thousands of years, or even longer. However, human culture changes dramatically over much shorter timescales – think of the changes over just the last century or so. In fact, it is only a few thousand years since most humans were still living essentially 'prehistoric' hunter-gather lifestyles. So although the environment humans live in is dramatically different in practically every way from our original prehistoric one, our brains and nervous systems will not have had time to adapt to any great extent, if at all. The extent to which our behaviours have changed is the crucial empirical question for which evidence has to be collected.\n\nThis perspective is multidisciplinary as it draws on a mixture of existing data, evidence and methods from psychological disciplines such as cognitive psychology, neuropsychology and group behaviour, as well as disciplines outside psychology, for example: • genetics • social anthropology: observations of current-day tribes living in hunter-gatherer groups • paleoanthropology: the collecting and documenting of ancient artefacts and tools, also prehistoric cave pictures and other art • primatology • ethology. Although it is clearly not possible to devise experiments to study the behaviours and social organisation of prehistoric humanity, evolutionary psychologists draw on data from the above disciplines to formulate possible hypotheses about different aspects of human behaviour. It may then be possible to examine actual human behaviour, to see if it fits in with the prediction, for example on the kinds of gender differences that would be expected to be found in male and female experiences of jealousy, based on Darwinian ideas about reproductive strategy. \n\nAnother area to which evolutionary psychology has been applied is in-group and out-group differences, i.e. the strong tendency to favour members of the 'in-group' to which one belongs, while being indifferent or even hostile to outsiders from an 'out-group'. This can be explained in evolutionary terms by seeing the potential 'adaptive value' this could have had for our ancestors living in small tribal groups. Group members who supported and co-operated with others within their group but were prepared to compete with outsiders for resources could plausibly be argued to have a survival advantage. Their superior access to resources would have enhanced their chances of survival, and hence reproduction. This would therefore have meant they had a greater chance of passing on their genes to future generations. So those genetic combinations which led to greater in-group/out-group differentiation would have been more likely to have been perpetuated (this is essentially what the 'adaptive value' of a particular behaviour refers to). While such behaviour towards in-groups and out-groups may well have been 'adaptive' for prehistoric hunter-gatherer communities, it is likely to be a good deal less fruitful under modern day conditions. For example, an evolutionary psychologist might try to analyze the conflict in Northern Ireland between Nationalists and Unionists in 'tribal' terms, as an expression of in-group/out-group behaviour. This might help understand some of the (to outsiders) apparently irrational and self-destructive aspects of many of the social interactions involved, If such social behaviours are indeed at least partly rooted in our evolutionary past, this understanding may suggest some contributions evolutionary psychology could make towards possible solutions. Explanations of social behaviour in evolutionary terms tend to be opposed by those psychologists who are influenced more by sociological viewpoints than biological, such as SOCIAL CONSTRUCTIONISTS (see the section on this). The latter argue that the major reasons for such conflicts are better seen in terms of socio-cultural forces, and the kinds of language in which they are framed. Unfortunately, there is rarely much attempt made in psychology to integrate such differing viewpoints. It is on the one hand important to be on guard against the kind of 'theoretical laziness' which ignores the profound conceptual and methodological conflict between such perspectives, in pursuit of a superficial eclecticism. However, it is perhaps another kind of 'laziness' which prevents proponents of one approach from even trying to get deeply inside alternative perspectives, with the aim of developing a genuinely multiple perspective viewpoint (even if this involves acknowledging some unresolved contradictions and disagreements). Humans are complex creatures, rarely explainable in terms of a single type of influence. This arguably requires psychologists to draw together as many perspectives as possible.