Published online by Cambridge University Press: 18 September 2020
In the Editors’ General Introduction to the first (2009) edition of this handbook, we acclaimed the success of the trait approach to personality (Matthews, Deary & Whiteman, 2009). Since that time, this approach has been boosted by growing consensus among researchers on the nature and measurement of the major traits, by remarkable advances in genetics and neuroscience, by increasing integration with various fields of mainstream psychology, and by applied utility – the maturity of the field is attested by the establishment of new journals, notably Personality Neuroscience (published by Cambridge University Press; see Corr & Mobbs, 2018). Such has been progress, trait researchers now pursue “normal science” (Kuhn, 1962): Common core assumptions are shared about the nature of personality and former vexatious positions are seen as far less relevant. There is a reasonable agreement on dimensional models, the importance of both biological and social factors, and the dependence of behavior on person × situation interaction. Within this consensus, a variety of still-burning questions remain (Fajkowska & Kreitler, 2018); for example, on the causal status of traits, sources of stability and change in personality over the lifespan, and the respective roles of trait and state factors in behavior.