Perception-action Coupling Impairments During Simulated Military Operational Stress Are Dependent On Time-of-day

Abstract

Perception-action coupling (i.e., reading and reacting to the environment) allows military personnel to maneuver safely and effectively through their environment. Exposure to military operational stress (e.g., caloric restriction, sleep loss) and around-the-clock operations may compromise perception-action coupling thereby impacting performance and safety. PURPOSE: To examine the effects of simulated military operational stress (SMOS) and time-of-day on perception-action coupling. METHODS: Fifty-seven military personnel (45 M, 12 W; 26.4 ± 5.6 years) completed a 5-day SMOS protocol. On day 0 (D0), D1 and D4, participants had 8-hour sleep opportunities and received 100% estimated caloric need. On D2 and D3, sleep was restricted and disrupted (two 2-hour sleep opportunities from 01:00 - 03:00 and 05:00 - 07:00), and caloric intake was restricted (50% estimated caloric need). Participants completed a tablet-based perception-action coupling task (PACT) on D1 (18:00, 22:00), D2 (04:00, 18:00, 22:00) and D3 (04:00, 18:00, 22:00). PACT requires participants make perceptual judgements about whether a series of virtual balls fits through virtual apertures of varying sizes. Outcomes of interest included response time (RT), lapses, and incorrect responses. Effects of day X time, day and time were examined using linear mixed models with post hoc pairwise comparisons (Tukey correction). RESULTS: Significant day X time effects were found for RT and lapses (both p < .01) and a significant effect of time was found for incorrect responses (p = .01). RT at 04:00 increased (got slower) by 2.2% across days, but decreased (got faster) by 6.8 and 3.5% across days at 18:00 and 22:00. Lapses at 04:00 increased across days but did not differ from D1 to D3 at 18:00 and 22:00. Participants made 39.3 and 6.0% more incorrect responses at 04:00 than at 18:00 and 22:00 respectively. CONCLUSIONS: Perception-action coupling performance was resilient to SMOS at 18:00 and 22:00, but deteriorated at 04:00. Reduced alertness (lapses), inaccurate perceptual judgements (incorrect responses), and slower response execution (RT) all contributed to perception-action coupling deficits at 04:00 which may reflect impaired performance capabilities of military personnel operating around-the-clock in the field. Support: DoD #W81XWH-17-2-0070