title: When two actions are easier than one: how inhibitory control demands affect response processing.
abstract: Numerous studies showed that the simultaneous execution of multiple actions is associated with performance costs. Here, we demonstrate that when highly automatic responses are involved, performance in single-response conditions can actually be worse than in dual-response conditions. Participants responded to peripheral visual stimuli with an eye movement (saccade), a manual key press, or both. To manipulate saccade automaticity, a central fixation cross either remained present throughout the trial (overlap condition, lower automaticity) or disappeared 200 ms before visual target onset (gap condition, greater automaticity). Crucially, single-response conditions yielded more performance errors than dual-response conditions (i.e., dual-response benefit), especially in gap trials. This was due to difficulties associated with inhibiting saccades when only manual responses were required, suggesting that response inhibition (remaining fixated) can be even more resource-demanding than overt response execution (saccade to peripheral target).
authors.affiliation: Würzburg University, Germany; RWTH Aachen University, Germany. Electronic address: lynn.huestegge@uni-wuerzburg.de.
authors.forename: Lynn
authors.initials: L
authors.lastname: Huestegge
authors.affiliation: RWTH Aachen University, Germany.
authors.forename: Iring
authors.initials: I
authors.lastname: Koch
mesh_terms: D000328:Adult; D056344:Executive Function / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D011930:Reaction Time / Q000502:physiology*; D012438:Saccades / Q000502:physiology; D055815:Young Adult
keywords: Dual-response benefits; Dual-task performance; Executive control; Eye movements; Gap effect; Saccade inhibition