title: Reduced motor preparation during dual-task performance: evidence from startle.
abstract: Previous studies have used a secondary probe reaction time (RT) task to assess attentional demands of a primary task. The current study used a startling acoustic stimulus (SAS) in a probe RT paradigm to test the hypothesis that attentional resources would be directly related to limitations in response preparation. Participants performed an easy or difficult version of a continuous primary task that was either primarily motor in nature (pursuit tracking) or cognitive (counting backward). Concurrently, participants responded to an auditory cue as fast as possible by performing a wrist extension secondary movement. On selected trials, the auditory cue was replaced with a SAS (120 dB), which is thought to involuntarily trigger a prepared response and thus bypass any response initiation bottleneck that may be present when trying to perform two movements. Although startle trials were performed at a shorter latency, both non-startle and startle probe trials resulted in a delayed RT, as compared to single-task trials, consistent with reduced preparation of the secondary task. In addition, analysis of SAS trial RT when a startle indicator was present versus absent provided evidence that the secondary task was at a lowered state of preparation when engaged in the cognitive primary task as compared to a motor primary task, suggesting a facilitative effect on preparatory activation when both the primary and secondary tasks are motoric in nature.
authors.affiliation: School of Kinesiology, University of British Columbia, War Memorial Gymnasium 210-6081 University Boulevard, Vancouver, BC, V6T 1Z1, Canada, dmaslovat@langara.bc.ca.
authors.forename: Dana
authors.initials: D
authors.lastname: Maslovat
authors.forename: Neil M
authors.initials: NM
authors.lastname: Drummond
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carter
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Carlsen
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011571:Psychoacoustics; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology*; D055815:Young Adult