| 1. |
- Dahlman, Joakim, 1974-, et al.
(författare)
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Could sound be used as a strategy for reducing symptoms of perceived motion sickness?
- 2008
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Ingår i: Journal of NeuroEngineering and Rehabilitation. - : Springer Science and Business Media LLC. - 1743-0003. ; 5:35
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Tidskriftsartikel (refereegranskat)abstract
- Background: Working while exposed to motions, physically and psychologically affects a person. Traditionally, motion sickness symptom reduction has implied use of medication, which can lead to detrimental effects on performance. Non-pharmaceutical strategies, in turn, often require cognitive and perceptual attention. Hence, for people working in high demand environments where it is impossible to reallocate focus of attention, other strategies are called upon. The aim of the study was to investigate possible impact of a mitigation strategy on perceived motion sickness and psychophysiological responses, based on an artificial sound horizon compared with a non-positioned sound source.Method: Twenty-three healthy subjects were seated on a motion platform in an artificial sound horizon or in non-positioned sound, in random order with one week interval between the trials. Perceived motion sickness (Mal), maximum duration of exposure (ST), skin conductance, blood volume pulse, temperature, respiration rate, eye movements and heart rate were measured continuously throughout the trials.Results: Mal scores increased over time in both sound conditions, but the artificial sound horizon, applied as a mitigation strategy for perceived motion sickness, showed no significant effect on Mal scores or ST. The number of fixations increased with time in the non-positioned sound condition. Moreover, fixation time was longer in the nonpositioned sound condition compared with sound horizon, indicating that the subjects used more time to fixate and, hence, assumingly made fewer saccades.Conclusion: A subliminally presented artificial sound horizon did not significantly affect perceived motion sickness, psychophysiological variables or the time the subjects endured the motion sickness triggering stimuli. The number of fixations and fixation times increased over time in the non-positioned sound condition.
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| 2. |
- Dahlman, Joakim, 1974-, et al.
(författare)
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Effects of Motion Sickness on Encoding and Retrieval
- 2010
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Tidskriftsartikel (refereegranskat)abstract
- Objective: In this study, possible effects of motion sickness on encoding and retrieval of words were investigated. Background: The impact of motion sickness on human performance has been studied with regards to psychomotor functions and over learned skills, as well as to novel situations requiring encoding and retrieval skills through the use of short term memory. In this study, possible effects of motion sickness on encoding and retrieval of words were investigated. Method: Forty healthy participants, half of them males, performed a continuous recognition task (CRT) during exposure to a motion sickness triggering optokinetic drum. The CRT was employed as a measurement of performance and consisted of encoding and retrieval of words. The task consisted of three consecutive phases 1) encoding of familiar words; 2) encoding and retrieval of words under the influence of motion sickness; 3) retrieval of words after exposure. Results: Data analysis revealed no significant differences in the ability to encode or retrieve words during motion sickness compared with a control condition. In addition, there were no significant correlations between the level of motion sickness and performance of the CRT. Conclusion: The results indicate that encoding and retrieval of words are not affected by moderate levels of motion sickness. Application: This research has implications for operational settings where professionals experience moderate levels of motion sickness.
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| 3. |
- Dahlman, Joakim, 1974-, et al.
(författare)
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Performance and Autonomic Responses during Motion Sickness
- 2009
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Ingår i: Human Factors. - : SAGE Publications. - 0018-7208 .- 1547-8181. ; 51:1, s. 56-66
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of the study was to investigate how motion sickness, triggered by an optokinetic drum, affects short term memory performance and to explore autonomic responses to perceived motion sickness. Background: Previous research has found motion sickness to decrease performance, but it is not known how short term memory in particular is affected. Method: Thirty-eight healthy participants performed a listening span test while seated in a rotating optokinetic drum. Measurements of motion sickness, performance, heart rate, skin conductance, blood volume pulse, and pupil size were performed simultaneously throughout the experiment. Results: A total of 16 participants terminated the trial due to severe nausea, while the other 22 endured the full 25 minutes. Perceived motion sickness increased over time in both groups, but less among those who endured the trial. Short term memory performance decreased towards the end for those who terminated, while it increased for the other group. Results from the measured autonomic responses were ambiguous. Conclusion: The present study concludes that performance, measured as short term memory, declines as perceived motion sickness progresses. Application: This research has potential implications for command and control personnel in risk of developing motion sickness.
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| 4. |
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| 5. |
- Dahlman, Joakim, 1974-
(författare)
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Psychophysiological and Performance Aspects on Motion Sickness
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Motion sickness is not an illness, but rather a natural autonomic response to an unfamiliar or specific stimulus. The bodily responses to motion sickness are highly individual and contextually dependent, making them difficult to predict. The initial autonomic responses are similar to the ones demonstrated when under stress. When under the influence of motion sickness, motivation and ability to perform tasks or duties are limited. However, little is known about how specific cognitive functions are affected. Furthermore, standard mitigation strategies involve medications that induce fatigue or strategies that require cognitive capabilities. Both of them may result in reduced capability to perform assigned tasks or duties. Hence, there is a need for alternative mitigation strategies.The aim of the thesis was to study psychophysiological and performance aspects on motion sickness. The long-term goal is to provide strategies for mitigation and prevention of motion sickness by identifying psychophysiological responses as predictors for both wellbeing and performance. This thesis comprises four studies, in which 91 participants were exposed to two different motion sickness stimuli, either an optokinetic drum or a motion platform. Before the tests, a method for extracting fixations from eye-tracking data was developed as a prerequisite for studying fixations as a possible mitigation strategy for reducing motion sickness. During exposure to stimuli that triggers motion sickness, performance was studied by testing short-term memory and encoding and retrieval. In the final study, the effects of an artificial sound horizon were studied with respect to its potential to subconsciously function as a mitigating source.The results of the measurements of the psychophysiological responses were in accordance with previous research, confirming the ambiguity and high individuality of the responses as well as their contextual dependencies. To study fixations, a centroid mode algorithm proved to be the best way to generate fixations from eye-movement data. In the final study, the effects of the sound horizon were compared to the effects of a non-positioned sound. In the latter condition, both fixation time and the number of fixations increased over time, whereas none of them showed a significant time effect in the sound horizon condition. The fixation time slope was significantly larger in the non-positioned sound condition compared to the sound horizon condition. Number of fixations, heart rate, and skin conductance correlated positively with subjective statements that referred to motion sickness. Among participants that were susceptible to motion sickness symptoms, short-term memory performance was negatively affected. However, no effects of motion sickness on encoding and retrieval were found, regardless of susceptibility.Future studies should continue focusing on autonomic responses and psychological issues of motion sickness. Factors such as motivation, expectancies, and previous experiences play a major and yet relatively unknown role within the motion sickness phenomena.
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| 6. |
- Sjörs, Anna, 1981-, et al.
(författare)
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Effects of motion sickness on encoding and retrieval performance and on psychophysiological responses
- 2010
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Tidskriftsartikel (refereegranskat)abstract
- Motion sickness has previously been found to deteriorate performance, e.g., regarding psychomotor functions and short term memory. Sustained ability to perform, despite motion sickness, is crucial in complex working environments. This study focuses on effects of motion sickness on encoding and retrieval of words through the use of long term memory. In addition, the temporal development of different psychophysiological responses and their relationship with perceived motion sickness were investigated. Forty healthy participants performed an encoding and retrieval task during exposure to an optokinetic drum. The results were compared with data from 20 controls that performed the task without motion sickness exposure. Measurements of heart rate, heart rate variability, skin conductance, blood volume pulse, respiration rate, and skin temperature were made throughout optokinetic drum exposure. Data analyses revealed no significant effects of moderate levels of motion sickness on the ability to encode or retrieve words. We found positive relationships between subjective motion sickness ratings and heart rate, blood volume pulse and skin temperature whereas respiration rate was negatively related to perceived motion sickness. The psychophysiological measurements did not show consistent patterns of sympathetic activation and parasympathetic withdrawal, as could be expected. Hence, they are not recommended as predictors of motion sickness.
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| 7. |
- Alkaissi, Aidah, et al.
(författare)
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P6 acupressure increases tolerance to nausogenic motion stimulation in women with high risk for PONV
- 2005
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Ingår i: Canadian Journal of Anesthesia. - 1496-8975. ; 52, s. 703-709
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: In a previous study we noticed that P6 acupressure decreased postoperative nausea and vomiting (PONV) more markedly after discharge. As motion sickness susceptibility is increased by, for example, opioids we hypothesized that P6 acu-pressure decreased PONV by decreasing motion sickness susceptibility. We studied time to nausea by a laboratory motion challenge in a group of volunteers, during P6 and placebo acupressure. Methods: 60 women with high and low susceptibilities for motion sickness participated in a randomized and double-blind study with an active P6 acupressure, placebo acupressure, and a control group (n = 20 in each group). The risk score for PONV was over 50%. The motion challenge was by eccentric rotation in a chair, blindfolded and with chin to chest movements of the head. The challenge was stopped when women reported moderate nausea. Symptoms were recorded. Results: Mean time to moderate nausea was longer in the P6 acu-pressure group compared to the control group. P6 acupressure = 352 (259–445), mean (95% confidence interval) in seconds, control = 151 (121–181) and placebo acupressure = 280 (161–340); (P = 0.006). No difference was found between P6 and placebo acupressure or placebo acupressure and control groups. Previous severity of motion sickness did not influence time to nausea (P = 0.107). The cumulative number of symptoms differed between the three groups (P < 0.05). Fewer symptoms were reported in the P6 acupressure compared to the control group P < 0.009. Overall, P6 acupressure was only marginally more effective than placebo acupressure on the forearms. Conclusion: In females with a history of motion sickness P6 acu-pressure increased tolerance to experimental nauseogenic stimuli, and reduced the total number of symptoms reported.
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| 8. |
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| 9. |
- Bergdahl, Björn, et al.
(författare)
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In the Forefront of Development:The New Undergraduate Medical Curriculu
- 2006. - 1
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Ingår i: Celebrating the Past by Expanding the Future: The Faculty of Health Science, Linköping University 1986–2006. - Linköping : Linköping University Electronic Press. - 9185643076 ; , s. 98-102
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Cros, Olivier, 1975-
(författare)
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Image Analysis and Visualization of the Human Mastoid Air Cell System
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- From an engineering background, it is often believed that the human anatomy has already been fully described. Radiology has greatly contributed to understand the inside of the human body without surgical intervention. Despite great advances in clinical CT scanning, image quality is still related to a limited amount X-ray exposure for the patient safety. This limitation prevents fine anatomical structures to be visible and, more importantly, to be detected. Where such modality is of great advantage for screening patients, extracting parameters like surface area and volume implies the bone structure to be large enough in relation to the scan resolution.The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented on a CT scan. Any statistical analysis will be biased towards air cells of smaller size. To allow a complete representation of the mastoid air cell system, a micro-CT scanner is more adequate. Micro-CT scanning uses approximately the same amount of X-rays but for a much longer exposure time compared to what is normally allowed for patients. Human temporal bone specimens are therefore necessary when using such scanning method. Where the conventional clinical CT scanner lacks level of minutes details, micro-CT scanning provides an overwhelming amount of fine details.Prior to any image analysis of medical data, visualization of the data is often needed to learn how to extract the structures of interest for further processing. Visualization of micro-CT scans is of no exception. Due to the high resolution nature of the data, visualization of such data not only requires modern and powerful computers, but also necessitates a tremendous amount of time to adjust the hiding of irrelevant structures, to find the correct orientation, while emphasising the structure of interest. Once the quality of the data has been assessed, and a strategy for the image processing has been decided, the image processing can start, to in turn extract metrics such as the surface area or volume and draw statistics from it. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this bone awakens the curiosity of the experimenter, especially with the correct visualization settings.This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously applied for conventional clinical CT scannings. The study compared current resul s with previous studies, with successive downsampling the data down to a resolution found in conventional clinical CT scanning. The results from the statistical analysis showed that all the small mastoid air cells, that cannot be detected in conventional clinical CT scans, do heavily contribute to the estimation of the surface area, and in consequence to the estimation of the surface area to volume ratio by a factor of about 2.6. Such a result further strengthens the idea of the mastoid to play an active role in pressure regulation and gas exchange.Discovery of micro-channels through specific use of a non-traditional transfer function was then reported, where a qualitative and a quantitative preanalysis was performed are described. To gain more knowledge about these micro-channels, a local structure tensor analysis was applied where structures are described in terms of planar, tubular, or isotropic structures. The results from this structural tensor analysis, also reported in this thesis, suggest these micro-channels to potentially be part of a more complex framework, which hypothetically would provide a separate blood supply for the mucosa lining the mastoid air cell system.
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