Introduction

The previous chapter dealt with the validity of GMA (general mental ability) as a predictor of job and training performance, as well as other work-related outcomes. In the current chapter, we discuss the predictive power of personality traits.

The question then emerges as to what is the difference between GMA and personality traits, and this is a question for which only one simple answer exists: traditionally (in personnel selection as well as in the wider context of psychological assessment), GMA is measured or tested via objective performance tests (such as those discussed in Section 6.6 and 6.7), whereas personality traits are assessed via subjective inventories, notably self- or other-reports (but especially self-reports). In that sense, one can distinguish between cognitive abilities and personality traits on the basis of assessment methods, whereby the former reflect individual differences in the capacity to identify correct responses to a standardised test (verbal or non-verbal), whereas the latter reflect individual differences in general behavioural tendencies, assessed only subjectively, that is, through people's accounts (one's own or others'). This led to a now well-established distinction in psychology to refer to cognitive abilities in terms of maximal performance and personality traits in terms of typical performance (Cronbach & Gleser, 1965), though in the case of personality traits ‘behaviour’ is a more accurate term than ‘performance’.