Differential psychology, which analyzes variations in behavior of people, has come a long way since Galton founded his anthropometry laboratory, a milestone in the study of individual differences. Today, this branch of psychology focuses its efforts on determining the relative influences of inheritance and environment on behavior.
In this article, we will briefly explain the historical development of differential psychology, describe the objectives and methods of this discipline, and clarify in which it differs from the psychology of personality, A very similar discipline in some respects.
History of differential psychology
In the middle of the 19th century the monk Gregor Mendel conducted the first genetic studies of which there is evidence. Using peas, Mendel determined the laws of heredity, made progress on the future concept of “gene” and coined the terms “dominant” and “recessive” in relation to the heritability of biological traits.
A few decades later Francis Galton, parent of Charles Darwin, Became a pioneer of differential psychology and personality thanks to the development of psychometry. Francis Galton’s pupil and protégé, mathematician Karl Pearson, made fundamental contributions to the field of statistics and challenged Mendelian laws.
The rise of behaviorism diminished the influence of differential psychology, which resurfaced in the 1960s and 1970s with the publication of Behavioral Genetics, John Fuller and Bob Thompson. these authors introduced in the discoveries of genetics in differential psychology which explained phenomena such as mutations and polygenic inheritance.
Despite advances in differential psychology and behavioral genetics, it remains difficult to separate hereditary and environmental influences from the study of human behavior and mind.
Objectives of this discipline
The main objective of differential psychology is quantitatively study the behavioral differences between individuals. Theorists and researchers in this discipline seek to determine the variables that cause differences in behavior and influence their manifestation.
Differential psychology focuses on three types of variation: interindividual (differences between one person and the rest), intergroup, which takes into account variables such as biological sex or socioeconomic level, and intraindividuals, which compare the behavior of the same person over time or in different contexts.
Although differential psychology is often confused with that of personality, the branch in question studies a wide variety of subjects: intelligence, self-concept, motivation, health, Values, interests … However, it is true that the contributions of differential psychology to personality and intelligence are better known.
Since its inception, the psychology of individual differences has been applied in educational and professional fields, although its usefulness depends on the phenomena studied. It is also important to mention the usual relationship of differential psychology with eugenics, which aims to “improve” the genetics of populations.
Differential psychology useful in particular statistical methods; thus, it works with large sample subjects and data is analyzed using a multivariate approach. In this way, experimental control elements are introduced which allow relationships to be established between variables. The use of observational and experimental methods is also common.
There are three types of research plans characteristic of differential psychology: those which analyze the similarities between parents, plans with animals, and those which study individuals raised in special contexts. From this last type of conception, we can highlight studies with adopted children, as well as the famous case of the wild child of Avairon.
Among family surveys studies with monozygotic twins stand outAs they are genetically identical and their differences therefore depend on the environment. However, and despite the obvious advantages of such designs, it is difficult to distinguish the relative influences of the specific and shared environment.
Genetic studies in animals can be useful due to the high rate of reproduction of some species and the ease of experimentation with non-humans, but they pose ethical problems and the results obtained are often impossible to generalize to humans.
How is it different from personality psychology?
Unlike differential psychology, which is primarily quantitative in nature, personality psychology focuses its efforts on the behavioral causes, characteristics, and consequences of interindividual variability.
On another side, the psychology of individual differences does not only analyze the personalityBut is also interested in other aspects, such as intelligence, socio-economic variables and certain patterns of behavior, such as criminal behavior.
In terms of methodology, differential psychology relies to a greater extent on studies that delineate the relative influence of heredity and environment on given variables. In contrast, personality psychology primarily uses correlational and clinical methods. Both emphasize experimental methodology.
Anyway, the field of study of these two disciplines frequently overlaps. In the realm of temperament and character, personality psychology studies the many facets of variations in behavior, while differential psychology quantifies them and addresses other aspects of human nature as well.