Task confusion after switching revealed by reductions of error-related ERP components.

While response delays after task switching have been widely used as an index to investigate the limits of cognitive flexibility, little is known about their counterpart in error rates. It has been hypothesized that at least some postswitching errors are not caused by simple response errors but by task confusion, which refers to the establishment and execution of an incorrect task set. The aim of the current study is to provide evidence for this hypothesis. Using a multitrial paradigm, we firstly dissociated task confusion from simple cue encoding failure, and then measured the error-related negativity (ERN) and the following error positivity (Pe) as indices of the brain's error processing. We predicted that task confusion, if it exists, would cause ambiguity to the criteria of correct response, and therefore attenuate error processing. Results confirmed our prediction, suggesting that task confusion actually occurs after switching.