This investigation used an experimental design to examine how a visual imagery intervention and two levels of challenge would affect the flow experiences and performance of cadets engaged in Army ROTC marksmanship training. I employed MANCOVA analyses, with gender and prior marksmanship training experience as covariates, to assess cadets' (n = 127) marksmanship performance and flow experiences. Findings revealed that the use of visual imagery did not positively enhance flow and improve performance with statistical certainty. The results, however, might be practically significant because they showed that when cadets were faced with a more challenging situation and had engaged in visual imagery exercises, they were more likely to outperform cadets in the same challenge condition who had not engaged in visual imagery exercises. On average, cadets in the high challenge condition who engaged in visual imagery exercises outperformed non-visual imagery cadets in the same condition by over one point on a six-point scale. Additional findings revealed that level of challenge did not affect flow experiences, which is counter to the postulates of flow theory. Level of challenge did, however, negatively impact performance. That is, when cadets were faced with a more challenging situation, they performed more poorly. Prior experience — and by extension skill level — was discovered to better facilitate flow experiences, as opposed to a balance of challenge and skills. Higher levels of prior marksmanship training experience were associated with cadets' potential to enter the flow state. Additionally, males rated flow significantly higher than their female counterparts. Males also significantly outperformed females. Implications for future research investigating how challenge and visual imagery affect flow experiences and performance in the context of Army ROTC marksmanship training are discussed. / Ph. D.

Special Weapons and Tactics (SWAT) operators are specially trained personnel that are required to carry equipment to perform high risk tasks. Given the need to carry this equipment, it is important to understand the potentially deleterious effect that the additional load may have on tactical performance. Furthermore, it is important to identify physical fitness characteristics that are associated with the potential decrement in performance. Therefore, the purpose of this study was to evaluate the effect of load carriage on tactical performance and identify fitness characteristics associated with any decrement in performance. Twelve male operators performed a simulated tactical test (STT) on a live firing range with (loaded condition) and without external equipment (unloaded condition) and completed a battery of physical fitness assessments. Time to complete the STT in the loaded condition increased by 7.8% compared to the unloaded condition. Nine of the 13 STT tasks were performed significantly slower in the loaded condition. VO2peak was negatively associated and fatigue index was positively associated with the overall STT delta time. These findings indicate that a higher aerobic capacity and lower anaerobic fatigability are related to a greater resilience to carrying a load while performing tactical tasks.

Military training and operations can place significant demands on cognitive and physical resources of service members, resulting in heightened stress and fatigue, elevated risk of accidents and injuries, and diminished cognitive and occupational performance. Transcutaneous electrical stimulation (TES) is a novel, non-invasive neuromodulatory technique being investigated as a means to improve alertness and preserve performance under stress with few-to-no side effects. Despite the recent increase in research using TES, few studies have explored the effects of stimulation of the trigeminal nerve on cognition and the human stress response. Therefore, the aims of this study were to elucidate the effects of TES on biochemical and physiological responses to stress, cognition, and marksmanship performance under cognitive load. Participants in this repeated measures, crossover-design study included 23 healthy male (n = 18) and female (n = 5) civilians and members of the military ranging in age from 19 to 37 (mean 24.00 ± 5.65) years. Study procedures occurred in the afternoon on five consecutive days, including two testing days involving administration of active or sham TES to the right supraorbital region of the face using a commercially-available device (Thync One, Cerevast Therapeutics). To evaluate the effects of TES on the stress response, participants were required to complete a prolonged, cognitively challenging target discrimination task using a simulated firing range, which has been previously demonstrated to induce a reliable stress response in human research volunteers. Computer-assisted cognitive tasks were administered before and after rifle marksmanship in order to provide complementary assessment of functional domains challenged during the marksmanship task. Salivary markers of cortisol and α-amylase were collected at several time points during the testing day, and electrocardiography (ECG) and photoplethysmography (PPG), both markers of heart rate variability and stress responding, were monitored continuously. Linear mixed models with random slopes were used to analyze the effect of stimulation condition (active versus sham TES) on marksmanship and cognitive, physiological, and salivary outcomes across the testing period and at each measurement time point. No significant effects of stimulation condition or the interactions between stimulation condition and measurement time point were found for salivary stress biomarkers (punadj range 0.12 – 0.98) or for cognitive (punadj range 0.25 – 0.88) and physical workload (punadj range 0.31 – 0.79). There were no significant effects of stimulation condition on time-series indicators of heart rate variability (punadj range 0.10 – 0.96) except for pNN50 when measured with PPG (β = -4.97, punadj = 0.04, padj = n.s., d < 0.01). There were, however, significant stimulation condition by time interaction effects on mean heart rate, mean R-R interval, SDNN, RMSSD, and pNN50 (punadj range 0.12 – 0.98, d range < 0.01 – 0.02), indicating that trigeminal TES using the Thync One device increased activity of both the sympathetic and parasympathetic nervous systems during marksmanship and cognitive testing. Similar effects were noted on frequency-series indicators of heart rate variability using both ECG and PPG, in which stimulation condition effects were noted on ECG high frequency absolute (β = 8.50, punadj < 0.01, padj = 0.01, d < 0.01) and relative powers (β = -8.54, punadj < 0.01, padj = 0.01, d < 0.01), as well as PPG very low frequency power (β = -367.98, punadj < 0.01, padj = n.s., d = 0.12). Effects of the interaction between stimulation condition and measurement time point were noted on very low, low, and high frequency powers (punadj range < 0.01 – 0.048, d range < 0.01 – 0.21), as well as the ratio of low- to high-frequency powers in ECG (punadj range < 0.01 – 0.048, d < 0.01 for all). These results also suggest that trigeminal TES increased activity of both the sympathetic and parasympathetic nervous systems during marksmanship and cognitive testing. Furthermore, significant effects of stimulation condition were noted on marksmanship shot accuracy (β = 0.14, punadj = 0.01, padj = n.s., d = 0.60) and distance of shots from the targets’ center of mass (β = -0.08, punadj = 0.02, padj = n.s., d = 0.56), indicating that trigeminal TES impaired shot accuracy. There were also significant condition-by-time interaction effects on target detection latency (β = 220.46, punadj = 0.04, padj = n.s., d = 0.49); significant impairments in shot latency observed during the first marksmanship session in the active TES condition only resolved by the second marksmanship session. There were no significant effects of TES on accuracy or response times for neuropsychological tasks assessing response inhibition, sustained attention, and working memory (punadj range 0.09 – 0.98). Active trigeminal TES did, however, significantly reduce the standard deviation of response times on a measure of sustained attention and response inhibition (β = -16.29, punadj = 0.045, padj = n.s., d = 0.43). Although the literature suggests that TES may benefit stress and performance, these results do not support that conclusion. Overall, these analyses found that TES using a commercially available device did not influence chemical biomarkers of stress, but did influence markers of physiological stress, as well as cognitive and marksmanship performance under high cognitive load. TES was associated with impairments in marksmanship performance as well as increases in both sympathetic and parasympathetic nervous system activity. Further studies using different stimulation parameters, including multiple sessions of stimulation, will be necessary to more fully characterize possible influences of trigeminal nerve stimulation on stress responding and marksmanship performance or other military relevant tasks. In addition, this project underscores the need for more investigation into the mechanisms of effect of the Thync One device and other devices applying TES of the trigeminal nerve.

Approved for public release; distribution in unlimited. / This thesis examines the effectiveness of the Indoor Simulated Marksmanship Trainer (ISMT) as a tool to train shooters in the fundamentals of marksmanship. Key concepts explored in the research are verification of skills transfer resulting from practice and the predictive value of simulated performance to proficiency at real task performance. There was no statistical difference in the scores of recruits trained in the ISMT versus a control group that was not trained in the ISMT. Scores on simulated firing were not a strong predictor of live fire performance. In a second experiment subjects were evaluated on their proficiency and improvement during un-coached practice at the task of simulated precision fire on a target at a simulated known distance of 300 yards from the shooters. After comparable amounts of practice in the ISMT, subjects who had not previously received formal marksmanship training failed to demonstrate levels of proficiency comparable to those subjects who had previously received formal marksmanship training in the military. Consequently, the research found no evidence to suggest the ISMT qualifies as a black box training apparatus capable of imparting skill through practice without the added presence of expert instruction or an existing knowledge of marksmanship techniques. / Major, United States Marine Corps

Background. The United States military relies on visual acuity standards to assess enlistment induction and military occupational specialty eligibility. In addition, the military recently instituted the Vision Readiness and Classification System to monitor Soldiers' combat vision readiness. The primary aim of this study was to investigate the relationship between visual acuity and marksmanship performance using a single blind randomized trial with the Engagement Skills Trainer 2000. Methods. Marksmanship performance was evaluated in 28 subjects under simulated day and night conditions with habitual spectacle prescription and contact lenses that created visual blur. Results. The relationship between visual acuity and marksmanship performance was found to have a statistically significant correlation of -0.735 with a 95% confidence interval from -0.790 to -0.669. Subsequently, 54 percent of the variance in marksmanship performance was accounted for by visual acuity. In addition, a panel poison regression model using an independent correlation structure revealed significant differences (p< .001) as visual acuity decreased from 20/25 to 20/50. Conclusions. Marksmanship performance decreases as visual acuity decreases. This relationship supports the use of a visual acuity requirement in the assessment of military readiness.

Thesis (Master of Military Studies)-Marine Corps Command and Staff College, 2008. / Title from title page of PDF document (viewed on: Feb 11, 2010).