interactionism
As a solution to the person-situation debate, an interactionist view has come to be widely accepted. The concept was first introduced by Lewin (1935) who proposed the formula B = f (P,S) which expresses that behaviour is a joint function of person and situation factors, originally in order to integrate behaviourism and psychoanalysis. According to Lewin, ‘every psychological event depends upon the state of the person and at the same time on the environment, although their relative importance is different in different cases’ (1936, p. 12). Although the importance of person-situation interactions had been stressed early, it was only after Mischel’s attack on the trait concept (1968) that interactionist research received more attention. Since the mid-70s, a ‘modern’ interactionist view of personality has been prevalent which is a compromise that dismisses the conflict between situationism and trait theory. According to Buss (1977), one must distinguish between two different concepts of interactionism. These have evolved out of four sub-perspectives of the person-situation controversy: the pure situationist position: B = f (S) behaviour is a function of the environment the pure trait position: B = f (P) behaviour is a function of the person the pure cognitive position: S = f (P) how a situation is perceived depends on individual personality characteristics, the environment or situation is construed by the person via certain cognitive processes the pure social learning position: P = f (S) person or individual differences variables are a function of the environment or the social learning history of a person The first two positions taken together provide the basic components of the mechanistic or statistical interaction model originally suggested by Kurt Lewin (1935): B = f (P,S). The way in which the formula is written is deceptive, because it suggests that personality and situation affect behaviour independently of each other. This is, however, not what the term ‘interaction’ means. An interaction is the influence that the particular combination of both variables has on behaviour. Lewin’s interaction concept is based on the assumption of a unidirectional causal relationship between person and situation as independent variables and behaviour as the dependent variable. Currently missing, please find in Krahe Figure 1. The mechanistic or statistical interaction model (P = person variables, S = situation variables, B = behaviour). The model is also called a statistical model, because it is captured in the statistical Analysis of Variance (ANOVA) framework. If used for the analysis of behaviour that is determined by both person and situation factors, an ANOVA allows to determine how much of the overall observed variability in behaviour is due to the effect of person variables, situation variables, their interaction, and error.