Errors are foreshadowed in brain potentials associated with action monitoring in cingulate cortex in humans

Previous studies have reported electrophysiological brain activity that is modulated when subjects commit errors in speeded reaction time tasks. This activity is thought to index an action monitoring system in anterior cingulate cortex that signals the need for performance adjustments to minimize the risk of future errors. Consistent with this view, we report here that performance errors are foreshadowed in a modulation of this brain activity on the immediately preceding trial. We propose that this modulation reflects fluctuations in the efficiency of the action monitoring system, which may occasionally compromise subsequent performance and thus comprise a prelude to performance errors.