Tim Dunn

• PhD
• Principal Investigator at Naval Health Research Center

Introduction A primary hazard of working in cold maritime environments is the potential for a substantial man overboard situation in freezing waters. Sudden cold-water immersion (CWI) triggers the cold shock response (CSR), which consists of cardiorespiratory responses that increase the chance of drowning. If cold shock response severity can be mit...

As automation becomes increasingly integrated into complex military tasks, and its role in supporting human performance under fatigue warrants careful evaluation. A specific military use case in which automated target cuing (ATC) is being integrated is undersea threat detection (UTD). These types of tasks demand sustained vigilance, accurate classi...

A literature review of studies investigating the relationship between marksmanship performance in simulators and live-fire ranges. The review indicates a small-to-moderate relationship and reveals significant limitations in previous studies. Recommendations for future research are provided.

There is little guidance in the literature concerning the number of simulations required when performing stochastic marksmanship duels to balance obtaining a reliable answer against obtaining that answer quickly. The present research fills this gap by investigating the reliability and computational efficiency of stochastic marksmanship duels with d...

A primary hazard of working in cold maritime environments is the potential for a substantial man overboard situation in freezing waters. Sudden cold-water immersion (CWI) triggers the cold shock response (CSR), which consists of cardiorespiratory responses that increase the chance of drowning. If CSR severity can be mitigated, life-saving actions m...

Introduction Poor acclimatization, high training demands, and sleeping conditions in the field can compromise the sleep of military personnel completing mountain warfare training. As chronic poor sleep can impact performance and recovery, individual differences in sleep may relate to differences in resilience during prolonged training. We character...

Introduction Extended wakefulness often covaries with effects of fatigue compounding performance decrements. Much work has sought to identify mitigation strategies. However, strategies that can be reasonably applied to operational tasks are lacking. In the current study, we leveraged recent motivational accounts of fatigue to determine the feasibil...

Wearable biometric tracking devices are becoming increasingly common, providing users with physiological metrics such as heart rate variability (HRV) and skin conductance. We hypothesize that these metrics can be used as inputs for machine learning models to detect independent variables, such as target prevalence or hours awake, objective task perf...

A common practice for those operating in cold environments includes repetitive glove doffing and donning to perform specific tasks, which creates a repetitive cycle of hand cooling and rewarming. This study aimed to determine the influence of intraday repeated hand cooling on cold-induced vasodilation (CIVD), sympathetic activation, and finger/hand...

Purpose. There is little guidance in the literature concerning the number of simulations required when performing stochastic marksmanship duels to balance obtaining a reliable answer against obtaining that answer quickly. The present research fills this gap by investigating the reliability and computational efficiency of stochastic marksmanship due...

Modeling efforts must account for the substantial variability of human performance. Although important to incorporate in many simulations with defense applications, properly accounting for variance can introduce unique challenges. Specifically, the modeling effort may impose reality constraints, where some physically impossible but mathematically r...

Cold-weather military operations can quickly undermine warfighter readiness and performance. Specifically, accidental cold-water immersion (CWI) contributes to rapid body heat loss and impaired motor function. This study evaluated the prevalence of hypothermia and critical hand temperatures during CWI. One-hundred seventeen (N = 117) military perso...

A common practice for those operating in cold environments includes repetitive glove doffing and donning to perform specific tasks, which creates a repetitive cycle of hand cooling and rewarming. This study aimed to determine the influence of intraday repeated hand cooling on cold-induced vasodilation (CIVD), sympathetic activation, and finger/hand...

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...

Purpose: Cold environments may deteriorate psychomotor performance due to slowing of neuronal signals, distractions caused by pain and discomfort, and loss of manual dexterity. The extent to which core temperature (T c) influences psychomotor performance in the cold has not been established. Therefore, psychomotor performance and T c were assessed...

Stress can impact perception, especially during use-of-force. Research efforts can thus advance both theory and practice by examining how perception during use-of-force might drive behavior. The current study explored the relationship between perceptual judgments and performance during novel close-combat training. Analyses included perceptual judgm...

Our metacognitive ability to monitor and evaluate our cognitive performance is central to efficient and adaptive behaviors. Research investigating this ability has focused largely on tasks that rely exclusively on internal processes (e.g., memory). However, our day-today cognitive activities often consist of mixes of internal and external processes...

Purpose Exposure to cold water immersion CWI deteriorates cognitive performance, which negatively impacts warfighter readiness. Recovery of performance following CWI may be mediated by improving thermal perception, and application of commercially-available heat packs may facilitate such a response. This work evaluated the effects of exogenous heat...

Introduction While sleep duration is known to affect next-day cognitive performance and alertness, largely in a dose-response manner, the effects of disrupted sleep (where one is awoken multiple times overnight, common in military settings) are much less understood. Therefore, we examined the effects of experimentally disrupted sleep on morning cog...

PURPOSE: Warfighters performance often slows in harsh environments as traditionally measured with response time (RT). While reflecting the cumulative duration of subprocesses, RT measurements are insufficient in providing insights into mechanisms underlying performance deterioration. Thus, understanding the degree to which each subprocess is affect...

PURPOSE: Cold water immersion (CWI) has the known mean effect of slowing response times (RTs). However, mean effects only show generic patterns and fail to account for variations across individuals. Understanding individual differences in RTs allows for better performance prediction. This requires more refined analysis. Therefore, ex-Gaussian and c...

Why are some actions evaluated as effortful? In the present set of experiments we address this question by examining individuals’ perception of effort when faced with a trade-off between two putative cognitive costs: how much time a task takes vs. how error-prone it is. Specifically, we were interested in whether individuals anticipate engaging in...

The notion that individuals adapt their behaviors in ways that are sensitive to the effortfulness of cognitive processing is pervasive in psychology. In the current set of experiments, we provide a test of a cue-utilization account of how individuals decide which course of action is more or less effortful. In particular, we contrast the influences...

Based on a recent metacognitive account, cognitive effort is the result of an inferential evaluation made over explicitly available cues. Following from this account, we present here a pre-registered experiment that tested the specific hypothesis that explicit awareness of cues that are aligned with cognitive demand is a prerequisite in avoiding ef...

Based on a cue-based metacognitive account, cognitive effort is the result of an inferential evaluation made over explicitly available cues. Following from this account, we present here a pre-registered experiment that tested the specific hypothesis that explicit awareness of cues that are aligned with cognitive demand is a prerequisite in avoiding...

The claim that humans adapt their actions in ways that avoid effortful processing (whether cognitive or physical) is a staple of various theories of human behavior. Although much work has been carried out focusing on the determinants of such behaviors, less attention has been given to how individuals evaluate effort. In the current set of experimen...

In the current set of experiments our goal was to test the hypothesis that individuals avoid courses of action based on a kind of metacognitive evaluation of demand in a Demand Selection Task (DST).Individuals in Experiment 1 completed a DST utilizing visual stimuli known to yield a dissociation between performance and perceived demand. Patterns of...

Individuals frequently make use of the body and environment when engaged in a cognitive task. For example, individuals will often spontaneously physically rotate when faced with rotated objects, such as an array of words, to putatively offload the performance costs associated with stimulus rotation. We looked to further examine this idea by indepen...