Individual differences in cognitive control: the role of psychoticism and working memory in set-shifting.

Set-shifting refers to a process of cognitive control which is shown through flexible behavioural adaptation to changes in task parameters or demands, such as the switching of an explicit rule (extra-dimensional rule shifting) or the reversal of a reinforcement-contingency (reversal-learning). Set-shifting deficits are widely documented in specific neuropsychological disorders, but seldom investigated in relation to normally-occurring individual differences. In a sample of healthy adults (N=78, 28% male), we demonstrate that Working Memory and trait Psychoticism have independent involvement in extra-dimensional rule shifting as measured using an analogue of the Wisconsin Card Sorting Test. Only Psychoticism, however, was involved in reversal-learning, as assessed using a recent modification of the Iowa Gambling Task. Individual differences in extra-dimensional rule shifting were explained in terms of rule abstraction speed, while individual differences in reversal-learning were explained in terms of response perseveration. These results clarify component processes in different forms of set-shifting, and highlight the role of individual differences, especially personality, in cognitive control.