Differential psychology

The Differential psychology is concerned with the differences between individuals in terms of psychological properties and states. Detailed descriptions, tests and measurements provide the basis for subsequent research: How do these differences develop from the genetic systems and the social influences? As these characteristics are interrelated and how they can be sorted? How do these characteristics change under different conditions of life and to what extent are they to influence action through education, psychotherapy, medication and Others?

In the study of psychology, differential psychology and personality psychology together form the compartment differential and personality psychology ( personality research).

Definition

Initially interested especially the differences in sensory abilities, response speed and intelligence functions, inter alia, skills as well as in relatively enduring personality traits. The approach then branched off because most of the features not found to be constant. Personality characteristics may change over time. Here, the human example of introversion and extraversion differ in the short and medium-term constancy of certain attribute characteristics and the extent of long-term plasticity, in youth and old age. Highly visible are the short-term changes of state, about the performance or of being during the day. In this regard, there are striking differences between people. Consequently, the differential psychology has to deal with:

Differences between individuals (inter - individual),
Differences ( variability ) within a person (intra - individual) and
Differences between people in terms of their variability ( inter-individual differences in intra-individual variability).

The Differential Psychology is concerned with all psychological features of human experience and behavior and refers, depending on the problem, the underlying physiological and neurophysiological differences as well as information on, inter alia, socio-psychological, socio-economic, ecological aspects a. ( Amelang et al 2006;. Asendorpf 2007). (see biopsychology, heritability, individuality, Constitution, Psychophysiology )

With their accurate descriptions and their methodological principles, the Differential Psychology provides the scientific basis of many other areas of psychology, particularly to the psychological assessment and applied psychology.

History

Among the pioneers of this research include Sir Francis Galton (1822-1911) with his Inquiries into Human Faculty and Its Development (1883 ) and James McKeen Cattell ( 1860-1944 ). Both studied in many people many functions, especially psycho- physiological characteristics such as sensory performance and response times. James McKeen Cattell wrote the book Mental tests and measurement (1890) and introduced the concept of a test in psychology. Hugo Münsterberg developed around 1891 tasks to verbal associations, arithmetic, reading and memory. By Hermann Ebbinghaus (1897 ) the idea of recording tasks for sentence completion in meaningful texts in the testing dates.

The French psychologist Alfred Binet (1857-1911) created along with Théodore Simon a serial task to measure mental performance of school children; it was the first intelligence test. The systematics and the research program of differential psychology were first developed by the German psychologist William Stern ( 1871-1938 ). Raymond B. Cattell (1905-1998) has this methodology, especially by the statistical method of factor analysis, and through his extensive work on a universal index of personality factors further expanded ( Cattell 1957).

William Stern Differential Psychology (1911 ) contains the first systematic program of this research direction. Features are developed by Stern everything "that is present in the individual as empirically Identifiable " (Stern 1911, p 20). He founded the Differential Psychology, demarcated by this view of the general psychology: What is considered uninteresting variability or as a measurement error in the general psychology, is the subject of differential psychology.

"Almost all efforts of scientific psychology until recently had this in common, that they generally preconceived problems. ( ... ) Now is justified such an abstraction, as long as it is clear from an inspection of the temporary limits of our ability; but the danger is obvious that one forgets an abstraction in front of you (...). Came but the researchers everywhere even against his will to mental characteristics; and when this was initially only for his generalizing viewing a source of error, so it was finally here, as in other cases, the history of science: from the error source itself was a problem, " (Stern 1911, p 1).

In addition, Stern called the " Special Psychology ", which deals with the study of selected sub-populations (among women, men, professional groups ) addresses. Both directions of research looking for universal laws and assume that people in their diversity yet are comparable - because of " general characteristics " (see common traits according to Allport 1937). Stern defines both the " differential psychology in the narrower sense " yet another issue and follows the scientific methodological distinction between the method of Nomothetik and idiography, that is, the search for general laws or the understanding of the individual and distinctive character (see figure ). Stern describes the individual- centric view:

" Again, the investigation is still nomothetic; but it approaches the limit of this research direction more so the tighter the radius of the group, the more specialized the typicality is, the essence of which is to be determined. The impact of the particular to the general is getting stronger, and the limit is reached where the individual individuality itself becomes a problem. Because individuality always means singularity. Each individual is in the same form anywhere else and never existing structures. To him probably confirm certain regularities embody in it probably certain types, it comparable in many respects with other individuals - but it's not completely on these principles, types, and equations, remains always a plus, by which it differs from other different individuals that are subject to the same laws and types. Thus, the individuality is the asymptote of the laws examined science. (...) When it. , In fact, as will some philosophers of science, the sole task of science is to find universally valid, then there is no psychology of the individual individuality. " (Stern 1911, p 4)

Methodology

Research on intelligence is in addition to the psychophysics of the area in which the methodology of psychological measurement was mainly developed. Here the modern psychological test methods and the theory of psychological tests emerged. The possibilities and limitations of these methods are still controversial, because there are fundamental differences between these often based on subjective judgment method and the natural sciences among others typical of the physics objective measurement. (see psychometrics, scaling).

In intelligence research is also clear that the differential psychology is not satisfied with the test methodological description, but asks how the observed differences come about: How much can be explained by hereditary predisposition, or by education? By what other conditions the intelligence performance is helped or hindered? The Differential Psychology also asks how the individual features are related. For the statistical method of correlation is often used. The height of the correlation coefficient expresses how closely two features, where nothing can be said, what causes this relationship or which variable the other controls. Other questions are: Is the intelligence performance in context, including with creativity or with certain personality characteristics, and the extent to allow the test results practically predict other differences, eg in the educational success and career success?

Already William Stern has distinguished four main approaches to differential psychology: the variation research focuses on the comparison of a feature in many individuals; the correlation research examines two or more features to many individuals; the psychographics considered an individual in regard to many features; the Komparationsforschung compares two or more individuals with regard to many characteristics. These strategies have since been further differentiated methodically and ( with the exception of psychographics, see biography) supplemented by appropriate statistical methods. Especially Raymond B. Cattell (1957 ) has taken the important step to differentiate the concept of psychological trait by defining observation or measurement opportunities in space and time, ie different situations and different time points, and corresponding correlation techniques. ( Amelang et al 2006;. Stemmler 1992)

For these approaches to differential psychology, the methodology Psychological testing and monitoring methods whose scientific quality is evaluated according to certain quality criteria developed. (see Psychological Assessment ).

The content validity (validity ) of a test value: how well intentioned it represents the property?
The formal reliability (reliability ): How accurate a test value by a second measurement of this type is reproducible?
The constancy over time (stability): how accurate are to reproduce the test scores in the short and long term?
Internal consistency: how closely related various individual features of the property intentioned together?
The generalization ability ( generalizability ): how well can the of - raised in a certain ( artificial ) situation analysis - test value to deduce the general form of this property in everyday life or in other life situations ( external validity, ecological validity )?

The concepts and methods of Differential methodology include on the test methodology beyond general study strategies, including many which are elaborated as methodologically sophisticated methods of research statistics. ( Amelang and Schmidt- Atzert 2006; Bortz and Döring 2006).

Feature areas and taxonomy

The work program of differential psychology includes all psychological characteristics. Their diversity and the various methods of investigation are among the reasons why there is so far no convincing system of order, no taxonomy of psychological characteristics. Even more important is the lack of a unified theory of personality, from which appropriate organizing principles could be derived. Therefore, only coarse gradations are possible, which are partly determined by the functional areas, some of the methods of investigation:

Sensory and motor skills, reaction time,
Intelligence functions, creativity, cognitive performance, special talents, language,
Learning, behavior, habits,
Social behavior, communication style, helpfulness,
Temperament characteristics such as mood, emotion, aggression,
Basic needs, motives, conflicts, life satisfaction, plans and objectives,
Modes of experience, consciousness changes,
Self-concepts, that is, the assessment of their own person, the Aussehenes and the talent from various viewpoints,
Social and political attitudes, interests, value orientations, ideological (religious ) beliefs,
Being ( wakefulness, mood, physical sensations ),
Physical characteristics, psychophysiological and neuropsychological variables.

Individual differences are to be described according to specific angles, eg by age differences, by gender difference, of socio-cultural differences or with respect to time differences of variability ( in the days running and course of the year, according to long-term trends and secular changes ) as well as comparison of relative variability of certain features and feature areas.

Idiographic approaches

The differential- psychological research has predominantly remained a correlation and variation research. In contrast, the biographical personality research has evolved to a large extent independent working direction (see biography biography research). The power required by psychologists such as William Stern, Gordon Allport, Hans Thomae individual- centric view means a great methodological challenge: to describe the individual character so that a comparison between the people remains possible. For a mediating way must be found between the general test and measurement methods that can not detect individual, and partly sympathetic, partly interpretive methods that explore approximately the special characteristics of a human being. (see idiography, individuality, interpretation, interview, Nomothetik, comprehension)

One approach could be for individuals characteristic profiles ( patterns ) of properties or methods in which the examinee bring their own psychological experiences and concepts, such as the roles construct test ( repertory grid test) by George A. Kelly. The term ipsative measurement is in contrast to the usual measurement is that no universal scaling is based, but it is judged solely for their own person and within his own experience, for example, by percentage and comparative estimate of how much a particular interest or a specific motivation compared to the other currently experienced interests. However, such individual- centered measurements are comparable only with major reservations between people. Therefore, these methods are more likely to detect changes in a person's psychological over time.

Research directions

Important directions of differential psychology continue research on intelligence and other cognitive functions, also overlooking the neuroscientific bases. These investigations often lead to the development of new tests and other study procedures and standardize internationally. Innovative methods such as computer -assisted data collection in daily new areas of research have been opened up, such as emotions, stress reactions or injuries ( Ambulatory Assessment) occurring in the days running. There are numerous tasks in the areas of occupational science, clinical psychology, educational psychology, supported primarily by the differential psychology, especially the psychology of personality and psychological assessment.

Nomothetic and idiographic George Kelly (psychologist) Human factors

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