Phasic Alertness Impairs Cognitive Control by Amplifying Competition between Evidence Accumulators

Abstract

Although phasic alertness generally benefits cognitive performance, it often increases the impact of distracting information, resulting in impaired decision-making and cognitive control. However, it is unclear why phasic alertness has these negative effects. Here, we present a novel, biologically informed account, according to which phasic alertness generates a transient, evidence-independent input (TEI) to the decision process. This shortens overall response times but also amplifies competition between evidence accumulators, thus slowing down decision-making and impairing cognitive control. The key hypotheses of this account are supported with pupil measurements and electrophysiological data from human decision-makers of either sex performing an arrow flanker task. We also show that a computational model of the flanker task that incorporates a TEI can reproduce the behavioral effects of phasic alertness but only when the evidence accumulators compete with each other through lateral inhibition. Our results reveal a close interplay between dynamic changes in alertness, cognitive control, and evidence accumulation.