Electrodermal activity (EDA), an indicator of arousal of the sympathetic nervous system, was investigated as a potential correlate of feeling-of-knowing (FOK) and tip-of-the-tongue (TOT) states. In Experiment 1, skin conductance was measured while participants answered general knowledge questions and made binary FOK and TOT judgments. Significant correlations were found between frequency of skin conductance responses (SCRs) and presence of both FOK and TOT states. In Experiment 2, warmth ratings were used and a follow-up clue session was added to offer participants the opportunity to resolve initially unanswered questions. SCR frequency during TOT states was significantly predictive of resolution during the clue period, although not as predictive as participants' warmth ratings. The potential of EDA as an on-line, non-intrusive measure of metamemory and memory retrieval is discussed.

Electrodermal activity (EDA), an indicator of arousal of the sympathetic nervous system, was investigated as a potential correlate of feeling-of-knowing (FOK) and tip-of-the-tongue (TOT) states. In Experiment 1, skin conductance was measured while participants answered general knowledge questions and made binary FOK and TOT judgments. Significant correlations were found between frequency of skin conductance responses (SCRs) and presence of both FOK and TOT states. In Experiment 2, warmth ratings were used and a follow-up clue session was added to offer participants the opportunity to resolve initially unanswered questions. SCR frequency during TOT states was significantly predictive of resolution during the clue period, although not as predictive as participants' warmth ratings. The potential of EDA as an on-line, non-intrusive measure of metamemory and memory retrieval is discussed.

Thesis (M.A.)--Boston University

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Brent Chamberlain / The physical environment influences mental health and inevitably well-being. While exposure to natural environments shows salubrious health benefits among those who maintain a consistent connection, little is known about how urban environments impact mental health. As urbanization increases worldwide, it is essential to understand the linkages between urbanized environments and public health. This project is guided by the research question: How do different environmental characteristics affect stress-related responses in users? The study will guide individual subjects (n > 30) to walk a designated route, exposing them to different architectural and environmental elements in downtown Manhattan, Kansas. Physiological biofeedback sensors, including electrodermal activity (EDA) and heart rate sensors, will be used monitor physiological behavioral changes; GPS will provide spatial location; and a GoPro camera will provide real-time first-person experience. Data from these sensors will be integrated into a temporal-spatial analysis to ascertain correlations between architectural and environmental elements in space and associated stress responses. Upon completing the walk, participants will take a brief survey asking for their perceptions, both quantitatively and qualitatively, of the different environments they encounter on the walk. Raw data collected from the biofeedback devices will be refined and analyzed spatially using GIS mapping software. This will allow us to visualize any associations between design characteristics and the elicited behavioral responses in order to determine the environmental characteristics that may illicit heightened stress responses. Analysis of the survey data will seek to identify any correlations between physiological and perception-based responses. The intent of the research is to provide a foundation for further studies into how public policy can be better informed and augmented to mitigate potential public health issues caused by urban design. Results will also inform architectural and engineering decision-making processes to further improve urban design by identifying characteristics that may improve or decrease mental health of those living and/or frequenting urban environments.

Chronic stress is endemic to modern society. If we could monitor our mental state, we may be able to develop insights about how we respond to stress. However, it is unfeasible to continuously annotate stress levels all the time. In the studies conducted for this dissertation, a minimally-invasive wearable sensor platform and physiological data processing methods were developed to analyze a number of physiological correlates of mental stress. We present a minimally obtrusive wearable sensor system that incorporates embedded and wireless communication technologies. The system is designed such that it provides a balance between data collection and user comfort. The system records the following stress related physiological and contextual variables: heart rate variability (HRV), respiratory activity, electrodermal activity (EDA), electromyography (EMG), body acceleration, and geographical location. We assume that if the respiratory influences on HRV can be removed, the residual HRV will be more salient to stress in comparison with raw HRV. We develop three signal processing methods to separate HRV into a respiration influenced and residual HRV. The first method consists of estimating respiration-induced portion of HRV using a linear system identification method (autoregressive moving average model with exogenous inputs). The second method consists of decomposing HRV into respiration-induced principal dynamic mode and residual using nonlinear dynamics decomposition method (principal dynamic mode analysis). The third method consists of splitting HRV into respiration-induced power spectrum and residual in frequency domain using spectral weighting method. These methods were validated on a binary discrimination problem of two psychophysiological conditions: mental stress and relaxation. The linear system identification method, nonlinear dynamics decomposition method, and spectral weighting method classified stress and relaxation conditions at 85.2 %, 89.2 %, and 81.5 % respectively. When tonic and phasic EDA features were combined with the linear system identification method, the nonlinear dynamics decomposition method, and the spectral weighting method, the average classification rates were increased to 90.4 %, 93.2 %, and 88.1 % respectively. To evaluate the developed wearable sensors and signal processing methods on multiple subjects, we performed case studies. In the first study, we performed experiments in a laboratory setting. We used the wearable sensors and signal processing methods to discriminate between stress and relaxation conditions. We achieved 81 % average classification rate in the first case study. In the second study, we performed experiments to detect stress in ambulatory settings. We collected data from the subjects who wore the sensors during regular daily activities. Relaxation and stress conditions were allocated during daily activities. We achieved a 72 % average classification rate in ambulatory settings. Together, the results show achievements in recognizing stress from wearable sensors in constrained and ambulatory conditions. The best results for stress detection were achieved by removing respiratory influence from HRV and combining features from EDA.

No description available.

With the growth of wearable devices capable of measuring physiological signals, affective computing is becoming more popular than before that gradually will remove our cognitive approach. One of the physiological signals is the electrodermal activities (EDA) signal. We explore how video stimulus that might arouse fear affect the EDA signal. To better understand EDA signal, two different medians, a scene from a movie and a scene from a video game, were selected to arouse fear. We conducted a user study with 20 participants and analyzed the differences between medians and proposed a method capable of detecting the highlights of the stimulus using only EDA signals. The study results show that there are no significant differences between two medians except that users are more engaged with the content of the video game. From gathered data, we propose a similarity measurement method for clustering different users based on how common they reacted to different highlights. The result shows for 300 seconds stimulus, using a window size of 10 seconds, our approach for detecting highlights of the stimulus has the precision of one for both medians, and F1 score of 0.85 and 0.84 for movie and video game respectively. / Master of Science / In this work, we explore different approaches to analyze and cluster EDA signals. Two different medians, a scene from a movie and a scene from a video game, were selected to arouse fear. By conducting a user study with 20 participants, we analyzed the differences between two medians and proposed a method capable of detecting highlights of the video clip using only EDA signals. The result of the study, shows there are no significant differences between two medians except that users are more engaged to the content of the video game. From gathered data, we propose a similarity measurement method for clustering different user based on how common they reacted to different highlights.

The first aim was to determine the baseline psychophysiological correlates in healthy subjects as a first necessary step towards the long-term goal of application the psychophysiological techniques in diagnostics mood and cognitive disorders. The second aim was to establish an easily applicable set of tests for evaluating emotional and memory processes by non-invasive psychophysiological methods. EEG, GSR, and eye-tracking data from 100 participants without any neurological or psychiatric disorders were obtained during watching affective pictures and performing memory tests. The spectral powers were computed for each 500 ms of the stimuli in theta, alpha, beta1, beta2 and beta3 bands in 12 areas of the brain. Lower alpha and higher beta3 power was related to higher emotional intensity. Negative emotions were distinguished in spatio-temporal changes of beta1 power and positive emotions showed higher beta3 power in right temporal region. Memory encoding showed higher alpha power. Lower theta and higher alpha power in central regions and overall increase of beta bands were observed during successful memory retrieval. A summary of spatio-temporal spectral correlates to emotional and memory processes was provided by this work. Key words: Electroencephalography, electrodermal activity, psychophysiology,...

Les variables neurovégétatives permettent d’évaluer l’état fonctionnel de l’individu, et représentent un intérêt pour mieux comprendre le comportement du conducteur, facteur déterminant de la sécurité routière. Ce travail est centré sur l’évaluation de la charge mentale du conducteur automobile par l’analyse de l’activité électrodermale. L’objectif est d’extraire les meilleurs indicateurs du signal électrodermal pour différencier la charge mentale induite par des situations de conduite réelle. L’analyse d’une trentaine d’indicateurs phasiques a permis de différencier des situations de conduite nominale, comparables en termes d’exigence comportementale mais différentes au niveau cognitif. Après traitement approprié du signal, en particulier en appliquant des transformations log, l’amplitude des réponses électrodermales est apparue comme un des indices les plus discriminants. Toutefois, les différences de charge mentale induites par les situations de conduite n’ont pas exactement correspondu à celles qui avaient été supposées. Une explication alternative mettant en avant des processus d’anticipation est proposée. Trois indicateurs toniques, dont deux sont nouveaux, ont ensuite été testés dans une expérience de double tâche, où une activité secondaire distractive était effectuée simultanément à la conduite. L’un s’est révélé inadapté au profil des signaux, mais les deux autres ont permis d’établir une hiérarchisation partielle de la surcharge induite. Particulièrement sensible à l’aspect cognitif de la distraction, l’évaluation psychophysiologique de la charge mentale par l’activité électrodermale apparaît complémentaire de l’analyse de la performance de conduite. / As an assessment tool for individual’s functional state, autonomic indices can help improving our knowledge of drivers’ behaviour, which is a central road safety causal factor. This work is focused on driver’s mental workload assessment, relying on electrodermal activity analysis. This is an attempt to highlight the most reliable electrodermal indices with the aim to distinguish accurately mental workload elicited by actual driving situations. The analysis of about thirty phasic indices, led to differentiate nominal driving situations. These were selected on the basis of comparable behavioural requirements, but of differences cognitive processes. After appropriate signal processing, (using log transformations in particular), electrodermal responses amplitude has the most potential to distinguish among experimental conditions. However, some of the differences about mental workload were not exactly those which were previously expected. An alternative interpretation of results highlighting anticipation processes is thus proposed. Tonic variations were then studied in a dual task experiment, including two new indices. The distractive power of several secondary tasks, performed while driving, was to be evaluated using these indices. One of the indices was unrelated to signals’ profile. Conversely, the two others gave a clear distinction of potential distraction elicited selectively by each secondary task. Mental workload was thus showed as being evaluated accurately using electrodermal activity analysis. Using objective physiological data and defining new electrodermal indices brought more reliability in the field of mental workload. Thus, electrodermal activity is a good candidate to complete data usually brought by tests or questionnaires.

Background. Although treatments for dizziness as a result of visual-vestibular mismatch (VVM) exist, the lack of prognostic information about this population affects the quality of their rehabilitation care. Despite numerous studies showing that individuals presenting with non-specific dizziness are likely to have VVM, and despite VVM being recognized by to the international classification of vestibular disorders by the Bárány Society, it remains unknown how prevalent this condition is. The VVM diagnostic questionnaire has not yet been generally accepted as a useful tool for diagnosis. There are inadequate criteria for prescribed vestibular rehabilitation for individuals with VVM, and little evidence to support the selection of treatment programs among this population. Treatment outcomes are not particularly successful because of a lack of guidelines. Studies have been performed that address dizziness severity, but no reliable biometric measurement has been developed yet. A potential measure of VVM could be responses of the autonomic nervous system (ANS) during vestibulo-visual challenges given the anatomical relationship between the vestibular system and the ANS. Individuals with both peripheral and central vestibular dysfunction exhibit symptoms and signs of autonomic dysfunction as a result of vestibulo-autonomic interactions. Moreover, changes in postural sway are a tangible indicator of the balance during any disturbance to the vestibular system. In this dissertation the use of measures of electrodermal activity (EDA) of the ANS and postural acceleration are explored in vestibular migraine (VM) individuals both with and without VVM. Purpose. The aims of this dissertation were to examine, in VM adults: 1) the presence of VVM and visual dependency in individuals presenting with complaints of dizziness using the VVM questionnaire and the Rod and Frame protocol, respectively; 2) the potential of EDA activity and postural responses to differentiate between VM and healthy individuals when accommodating for postural instability and visual-vestibular conflict; and 3) the effect of exposure to different visual contexts of VR environments on EDA phasic and tonic responses and postural responses in identified VM adults with VVM. Participants. Seventy-four participants with dizziness were enrolled in Aim 1 (70% female, mean age 45.4 ± 14.8 years), and a total of 45 participants (23 healthy, 45.5% female, mean age 34± 9 years) and (22 VM adults, 61% female, mean age 34.4 ± 8, including 12 VM adults with VVM, 77% female, mean age 34±9) were enrolled in the experimental studies for Aims 2 and 3. Methods. In Aim 1, the VVM questionnaire and the Rod and Frame protocol were used to test the presence of VVM and visual dependency, respectively. In Aims 2 and 3, a Shimmer 3 IMU sensor accelerometer was used to assess trunk acceleration in the anterior-posterior, medial-lateral, and vertical directions with different VR environments (STREET and SPACE). EDA measurements were assessed with a wireless wearable Shimmer 3 GSR+. Clinical measures of dizziness and mobility were concurrently tested. A linear mixed model was used to examine the effect of VM with and without VVM on standing balance and EDA activity. Results. The presence of VVM, headache, and visual dependency demonstrated a strong association. EDA activity and postural acceleration significantly differed between VM and healthy individuals. Specific subjective reporting tools, including ABC, VSS-SF, VVAS, and DHI, were reliable for distinguishing between VM and healthy individuals. Lastly, VM individuals with VVM exhibited significantly greater NPL of trunk accelerations in the vertical plane than VM individuals without VVM with the STREET environment compared to the SPACE environment. Conclusion. VVM and visual dependency could be risk factors for developing vestibular migraine and should be included in the examination protocol of those populations. Combining measures of EDA and trunk acceleration may provide objective measures of the severity of dizziness related to VVM. Results of this dissertation suggest that the use of EDA measures combined with NPL-Vert could provide potential neurophysiological biomarkers in identifying VVM in adults with vestibular migraines. Further, the correlation between the characteristics of the visual environment and the subjective dizziness outcome measure may contribute to establishing a threshold-tolerance basis for designing a vestibular rehabilitation program that will more precisely target symptom severity. / Physical Therapy