Basic Psychology: Differential psychology
Contents
- Introduction
- Importance of individual differences
- Areas of study
- Methods of research
Introduction
Differential psychology is the study of how people differ in their behaviour and the processes that underpin it. This is a discipline that creates classifications (taxonomies) of psychological differences between people. This differs from other aspects of psychology in that, while psychology is ostensibly a study of individuals, modern psychologists frequently study groups or try to discover general psychological processes that apply to all individuals. William Stern named and still refers to this branch of psychology as "differential psychology" in his book (1900)
While prominent psychologists such as Stern have been widely credited with coining the term "individual differences," historical records show that it was Charles Darwin (1859) who sparked scientific interest in the study of individual differences. Francis Galton, his half-cousin, pursued his interest in quantifying individual differences among people.
In assessing the efficacy of a new therapy, for example, the mean performance of the therapy in one treatment group may be compared to the mean efficacy of a placebo (or a well-known therapy) in a second, control group. Individual differences in reaction to experimental and control manipulations are treated as errors in this context, rather than as interesting phenomena to investigate. This method is used because psychological research is based on statistical controls that can only be applied to groups of people.
Importance of individual differences
Individuals can differ not only in their current state, but also in the magnitude or even the direction of their response to a given stimulus. Such phenomena, which are frequently explained in terms of inverted-U response curves, place differential psychology at the forefront of endeavours such as personalised medicine, in which diagnoses are tailored to an individual's response profile.
Areas of study
Personality, temperament (neuro-chemically based behavioural traits), motivation, intelligence, ability, IQ, interests, values, self-concept, self-efficacy, and selfesteem are all common topics in individual differences research (to name just a few). There are few "differential psychology" programmes left in the United States, despite the fact that research in this area is very active. Current researchers can be found in a wide range of applied and experimental programmes, such as clinical psychology, educational psychology, industrial and organisational psychology, personality psychology, social psychology, behavioural genetics, and developmental psychology programmes, particularly in neo-Piagetian theories of cognitive development.
Methods of research
Psychologists employ a variety of techniques to investigate individual differences. EEG, PET-scans, MRI, functional MRI, neurochemistry experiments with neurotransmitter and hormonal systems, caffeine and controlled drug challenges are examples of psychophysiological experiments performed on humans and other mammals. These techniques can be used to look for biomarkers of consistent, biologically based behavioural patterns (temperament traits and symptoms of psychiatric disorders). Other methods include behavioural experiments, which are used to see how different people behave in similar situations. Behavioural experiments, which include lexical and self-report methods in which people are asked to complete paper-based and computer-based forms prepared by psychologists, are frequently used in personality and social psychology.
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