Field Assessment of Cognitive Performance under Stress

Abstract

Performance decrements have frequently been reported in combat but it has been difficult to demonstrate the specific causal source of cognitive degradation sutficient to disrupt performance during military operations. In the present study, seventeen inhtiymen were assessed during both a oneweek simulated combat exercise and a p r a w n assault. Significant change did not occur during the one week exercise, however simple reaction time did increase following the assault. One planned field assessment occurred at the moment following a potentially serious medical event. A soldier perceived that he was experiencing heatstroke but medical evaluation indicated that he was still "fit for duty". Cognitive evaluation of his failing state was characterized by slow Simple Response Time and rapid and inaccurate responding on more complex response tasks. Fortunately, the soldier could return to duty but his scores slowly recovered, such that he returned to baseline levels two days later. The present infantry operational environment did not produce significant-information processing change in inhtrymen. However, significant performance cognitive decrements followed the specific acute event of assault that was perceived as life-threatening. As we demonstrate, increased reaction time after the assault is consistent with increased fatigue following an extended period in the infantry operating environment.

Cognitive Change in Special Forces Personnel following Stressful Survival Training

“…Memory tasks deteriorated most. This pattern differs from previous studies which found Logical Reasoning was most sensitive to the stress of physically demanding simulated combat (Harris & Hancock, 2003). Replication of Class 1 changes in Class 2 indicates a strong consistency in the cognitive processing changes produced by SERE training.…”

“…The appearance of decrements in complex cognitive task performance at the point at which SRT increased by approximately 20 ms is consistent with our previous studies that have found SRT diagnostic and that complex cognitive performance changes can be predicted by SRT changes (Harris et al, 2005;Harris & Hancock, 2003). The consistent appearance of cognitive performance deficits when SRT increases reach 20 ms suggests that SRT may provide an effective fitness for duty test.…”

“…However, the subsequent inclusion of Simple Response Time (SRT) and a more detailed analysis of within-session did find subtle cognitive changes following one week of high stress and only three hours of recovery (see Harris, Hancock, & Harris, 2005). Further, in some of our previous work, we have also found small changes in cognitive performance immediately following physically demanding work (Harris & Hancock, 2003). The present study examined the effect of high levels of combined physical and psychological stress immediately following SERE exposure and also monitored the recovery profile as it occurred during a twelve-hour, post-stress interval.…”

“…The cognitive battery selected provides a profile of six cognitive functions critical for decision making in military settings. Previous studies (Harris et al, 2005;Harris & Hancock, 2003) found that SRT changes preceded response time change in more complex tasks and the number of milliseconds by which SRT increased, actually predicted the level of deterioration of the more complex tasks. The present study served to further evaluate this covariation of SRT-cognitive functioning.…”

Development of an Operational Setting Specific Field Cognitive Assessment Procedure

“…The Automated Readiness Evaluation System (ARES) developed by Elsmore and Reeves (in press) is an extension of this battery and presents ANAM tasks on handheld computers. The ARES has proven to be a most useful method of assessing cognitive functioning in operational settings (Harris, & Hancock, 2003;Harris & Hancock, & Morgan, 2005), and component test profiles have been constructed for field settings that provide a profile of the cognitive capacities deemed to be important in those settings Harris, & Hancock, 2003;Harris, Hancock, & Morgan, 2005).…”