Дисертації з теми "Psychophysiological state"

A spacewalk, or extravehicular activity (EVA), is one of the most mission critical and physically and cognitively challenging tasks that crewmembers complete. With next-generation missions to the Moon and Mars, exploration EVA will challenge crewmembers in partial gravity environments with increased frequency, duration, and autonomy of operations. Given the distance from Earth, associated communication delays, and durations of exploration missions, there is a monumental shift in responsibility and authority taking place in spaceflight; moving from Earth-dependent to crew self-reliant. For the safety, efficacy, and efficiency of future surface EVAs, there is a need to better understand crew health and performance. With this knowledge, technology and operations can be designed to better support future crew autonomy. The focus of this dissertation is to develop and evaluate a psychophysiological monitoring tool to classify cognitive workload during an operationally relevant EVA task. This was completed by compiling a sensor suite of commercial wearable devices to record physiological signals in two human research studies, one at Virginia Tech and one at NASA Johnson Space Center. The approach employs supervised machine learning to recognize patterns in psychophysiological features across different psychological states. This relies on the ability to simulate, or induce, cognitive workload in order to label data for training the model. A virtual reality (VR) Translation Task was developed to control and quantify cognitive demands during an immersive, ambulatory EVA scenario. Participants walked on a passive treadmill while wearing a VR headset to move along a virtual lunar surface. They walked with constraints on time and resources, while simultaneously identifying and recalling waypoints in the scene. Psychophysiological features were extracted and labeled according to the task demands, i.e. high or low cognitive workload, for the novel Translation Task, as well as for the benchmark Multi-Attribute Task Battery (MATB). Predictive models were created using the K Nearest Neighbor (KNN) algorithm. The contributions of this dissertation span the simulation, characterization, and modeling of cognitive state. Ultimately, this work tests the limits of extending laboratory psychophysiological monitoring to more realistic environments using wearable devices, and of generalizing predictive models across participants, times, and tasks. This work paves the way for future field studies and real-time implementation to close the loop between human and automation.<br>Doctor of Philosophy<br>A spacewalk is one of the most important and physically and mentally challenging tasks that astronauts complete. With next-generation missions to the Moon and Mars, exploration spacewalks will challenge astronauts in reduced-weight environments (1/6 and 1/3 Earth's gravity) with longer, more frequent spacewalks and with less help from mission control. To keep astronauts safe while exploring there is a need to better understand astronaut health and performance (physical and mental) during spacewalks. With knowledge of how astronauts will respond to high workload and stressful events, we can plan missions and design tools that can best assist them during spacewalks on the Moon and Mars when help from Earth mission control is limited. Traditional tools of quantifying mental state are not suitable for real-time assessment during spacewalks. Current methods, including subjective surveys and performance-based computer tests, require time and attention to complete and cannot assess real-time operations. The focus of this dissertation is to create a psychophysiological monitoring tool to measure mental workload during a virtual reality (VR) spacewalk. Psychophysiological monitoring uses physiological measures, like heart rate and breathing rate, to predict psychological state, like high workload or stress. Physiological signals were recorded using commercial wearable devices in two human research studies, one at Virginia Tech and one at NASA Johnson Space Center. With machine learning, computer models can be trained to recognize patterns in physiological measures for different psychological states. Once a model is trained, it can be tested on new data to predict mental workload. To train and test the models, participants in the studies completed high and low workload versions of the VR task. The VR task was specifically designed for this study to simulate and measure performance during a mentally-challenging spacewalk scenario. The participants walked at their own pace on a treadmill while wearing a VR headset to move along a virtual lunar surface, while balancing their time and resources. They were also responsible for identifying and recalling flags along their virtual path. Ultimately, this work tests the limits of extending laboratory psychophysiological monitoring to more realistic environments using wearable devices, and of generalizing predictive models across participants, times, and tasks. This work paves the way for future field studies and real-time implementation to close the loop between human and automation.

Reversal theory (Apter, 1982) is a psychological theory of motivation, emotion, and personality that purports to explain human behaviour as well as experience. In 1999 Svebak proposed a triangular relationship between metamotivational dominance, sport preference and biological composition among elite athletes using a reversal theory framework. Svebak’s proposition would suggest that when three of these components match (e.g., telic dominant individual with slow-twitch muscle fibre predominance who participates in endurance activities), they have a higher probability of success, and of optimizing the joy of participating. However, this proposition has only been examined in elite athletes (Braathen & Svebak, 1990). The purpose of the present research was to examine whether components of Svebak’s triangular relationship could be demonstrated in the general population and to examine the relationships between dominance, state and physical performance. A series of four studies were conducted with subjects purposely sampled and allocated to telic and paratelic groups from a pool of individuals who initially completed the Paratelic Dominance Scale (PDS; Cook & Gerkovich, 1993). Subjects who scored higher than one standard deviation above the mean were classified as the paratelic dominant (PD), while those who scored lower than one standard deviation below the mean were classified as the telic dominant (TD) (Gerkovich, Cook, Hoffman, & O’Connell, 1998). Age, sex, preferred sports/exercise activity and frequency of exercise per week were recorded for each subject. In each study, state was manipulated via video stimuli into telic and paratelic in a crossover design before completing an exercise task, the subjects continued to watch the video stimuli for the duration of the exercise. Manipulation checks indicated that the video stimulus was successful in changing state. The Telic State Measure (TSM; Svebak & Murgatroyd, 1985) and Tension and Effort Stress Inventory (TESI; Svebak, 1993) were completed during each of the studies. The exercise performed in each study varied with 5 s isometric leg extension used in Study 1; 100 repetition isokinetic leg extensions in Study 2; 30 s Wingate test in Study 3 and ramped peak test in Study 4. Exercise preference in all four studies indicated that telic dominant individuals preferred endurance exercise activities, while paratelic dominant individuals preferred explosive exercise activities, supporting previous research (Cogan & Brown, 1999; Kerr, 1991; Kerr & Svebak, 1989; Svebak & Kerr, 1989). Physiological responses (EMG and HR for Studies 1 and 2; HRV and HR for Studies 3 and 4) showed mixed results. For the Study 1, EMG was employed to examine if either state or dominance influenced neural activation during isometric leg contraction, however no significant differences were found. Study 2, muscle tension was examined using EMG gradients during isokinetic leg exercise with results indicating dominance determining EMG gradients rather than state (gradients present in telic dominant individuals). HRV has never been investigated previously in relation to reversal theory. In both Studies 3 and 4 the majority of HRV components decreased after exercise as a result of vagal withdrawal. When examining metamotivational dominance/state and HRV variables, changes showed no statistical significance in both studies, but responses in HRV variables were observed in relation to differences between metamotivational dominance/state suggesting a need for further studies. Heart rate was measured in all four studies and results were consistent with telic dominant individuals having a lower resting heart rate. No significant differences were found between metamotivational dominance in relation to performance. However, across all four studies there was a tendency for paratelic dominant individuals to perform better during explosive/power activities while telic dominant individuals performed better during endurance activities, both groups tended to perform better in their preferred state. There was a strong tendency for telic dominant individuals to report higher levels of stress than the paratelic dominant individuals regardless of the state condition. State effects were observed for some of somatic emotions (i.e., excitement, relaxation, boredom and anxiety), while other emotions showed time effects due to the results of exercise in all four studies. Generally, both telic and paratelic dominant individuals were more excited and less bored at post-exercise; and telic dominant individuals were more anxious throughout the course of experiment. The present research has made contributions to reversal theory research by supporting previous findings in exercise preference and resting heart rates, and presenting new data on changes in stress and emotions in telic/paratelic state conditions during exercise. Furthermore, muscle tension, as indicated by EMG gradients, has been observed relative to state and HRV has been measured for the first time in relation to reversal theory, indicating possible links between HRV and metamotivational dominance/state. Methodological issues such as state manipulation and dominant group selection have contributed to the reversal theory research. The data provide some support for Svebak’s proposed triangular relationships among general populations.