Personality theories and models: An overview

The thesis of these volumes is that the study of personality traits has advanced towards " normal science " in the sense of a Kuhnian paradigm (cf. Eysenck, 1981; Kuhn, 1962). That is, most researchers in this area share a set of common core beliefs supported by empirical evidence. These include the stability of traits over time, a significant genetic and biological influence on personality, and relevance of traits to many areas of everyday life. Each one of these beliefs has been vigorously contested in the past, but the evidence in favour of each one is now overwhelming (Boyle & Saklofske, 2004; Matthews et al., 2003). At the same time, researchers do not subscribe to some crude biological determinism. The roles of gene-environment interaction in personality development and of person-situation interaction in determining behaviour are also well-established. Within the overall paradigm, trait models have also stimulated important and unresolved debates, including the optimal measurement framework for traits, the mechanisms that transmit causal effects of traits on behaviour, as well as the roles of cultural and social factors in moderating the nature of traits. The purpose of these handbooks is to review issues of both consensus and controversy. Contributors synthesize the state-of-the-art of the research on the core tenets of trait theory, such as behaviour genetics and trait stability, and present perspectives on unresolved issues such as the important role of culture. In addition, trait theory is only one scientific paradigm for personality research. Although the focus here is on trait models, the handbooks also seek to explore key points of contact and differences with traditional approaches to personality 2 (Campbell, Vol. 1) and with social-cognitive theory and methods (Cervone, Vol. 1; Shoda, Vol. 2). In this introductory chapter, we will outline the case that the trait model of personality constitutes normal science, and compare the trait perspective with alternative scientific approaches. We will also set out the key criteria that must be satisfied to build a successful trait theory, subdivided into formal and often quantitative criteria such as test-retest stability, and criteria that relate to the psychological meaning and construct validity of traits. As well, we will discuss some of the challenges to trait theory, and the directions the field may take in addressing these challenges. We will conclude the chapter by introducing the various contributions to Vol. 1, related to the pivotal issues previously discussed. Trait Theory as Normal …