Cold Entropy: Assessing Individual Differences in Cognitive Adaptability during Cold Stress

Abstract Human cognition unfolds in a multitude of environments, including those that are associated with extreme stressors. Successfully measuring and modeling behaviors in such environments is inherently difficult. The current effort aimed to assess variation in stability and flexibility of cognitive performance during cold stress, individual differences in errors, and physiological correlates. Fifty-seven service members completed cold water immersion during winter months. Individuals were required to immerse themselves in an outdoor pond for 10 minutes, reclothe into dry clothing, and attempt to rewarm. Simple reaction time and match-to-sample tasks were completed throughout the 90 minute procedure. To assess response stability, sample entropy was computed for the response time time-series of each task. Hierarchical clustering applied to sample entropy values identified two clusters of individuals. One highly affected group demonstrated low stability and weak flexibility by way of higher autocorrelation and more omission errors, and had lower hand temperature pre- and post-immersion. Results are discussed within the context of cold stress, adaptive behaviors, and cold stress.