Rumination and inhibition in task switching: no evidence for an association.

Rumination is typically defined as the perseverative focus of attention on negative internal thoughts and feelings, which can increase the risk of developing - and severity once developed - of depression. It is thought the perseveration is caused by a deficit in inhibitory control in ruminators. Congruent with this hypothesis, estimates of inhibition in task switching - the n-2 task repetition cost - are negatively associated with estimates of rumination. However, estimates of individual differences of n-2 task repetition costs are hampered by (a) measurement error caused by trial-wise variation in performance, and (b) recent evidence suggesting much of the n-2 task repetition cost measures interference in episodic memory, not inhibition. The aim of the current study was to revisit the question of the association between the n-2 task repetition cost and measures of rumination by (a) statistically accounting for measurement error by estimating n-2 task repetition costs via trial-level Bayesian multilevel modelling, and (b) controlling for episodic interference effects on estimates of n-2 task repetition cost by utilising a paradigm capable of doing so. The results provided no evidence for an association between rumination and n-2 task repetition costs, regardless of episodic interference.