The costly filtering of potential distraction: Evidence for a supramodal mechanism.

When dealing with significant sensory stimuli, performance can be hampered by distracting events. Attention mechanisms lessen such negative effects, enabling selection of relevant information while blocking potential distraction. Recent work shows that preparatory brain activity, occurring before a critical stimulus, may reflect mechanisms of attentional control aimed to filter upcoming distracters. However, it is unknown whether the engagement of these filtering mechanisms to counteract distraction in itself taxes cognitive-brain systems, leading to performance costs. Here we address this question and, specifically, seek the behavioral signature of a mechanism for the filtering of potential distraction within and between sensory modalities. We show that, in potentially distracting contexts, a filtering mechanism is engaged to cope with forthcoming distraction, causing a dramatic behavioral cost in no-distracter trials during a speeded tactile discrimination task. We thus demonstrate an impaired processing caused by a potential, yet absent, distracter. This effect generalizes across different sensory modalities, such as vision and audition, and across different manipulations of the context, such as the distracter's sensory modality and pertinence to the task. Moreover, activation of the filtering mechanism relies on both strategic and reactive processes, as shown by its dynamic dependence on probabilistic and cross-trial contingencies. Crucially, across participants, the observed strategic cost is inversely related to the interference exerted by a distracter on distracter-present trials. These results attest to a mechanism for the monitoring and filtering of potential distraction in the human brain. Although its activation is indisputably beneficial when distraction occurs, it leads to robust costs when distraction is actually expected but currently absent.