Eye Tracking during High Speed Navigation at Sea

Purpose: Professional high speed sea navigational procedures are based on turn points, courses, dangers and steering cues in the environment. Since navigational aids have become less expensive and due to the fact that electronic sea charts can be integrated with both radar and transponder information, it may be assumed that traditional navigation by using paper based charts and radar will play a less significant role in the future, especially among less experienced navigators. Possible navigational differences between experienced and non-experienced boat drivers is thus of interest with regards to their use of navigational aids. It may be assumed that less experienced navigators rely too much on the information given by the electronic sea chart, despite the fact that it is based on GPS information that can be questioned, especially in littoral waters close to land.Method: This eye tracking study investigates gaze behaviour from 16 experienced and novice boat drivers during high speed navigation at sea.Results: The results show that the novice drivers look at objects that are close to themselves, like instrumentation, while the experienced look more at objects far away from the boat. This is in accordance with previous research on car drivers. Further, novice boat drivers used the electronic navigational aids to a larger extent than the experienced, especially during high speed conditions. The experienced drivers focused much of their attention on objects outside the boat.Conclusions: The findings verify that novice boat drivers tend to rely on electronic navigational aids. Experienced drivers presumably use the navigational aids to verify what they have observed in the surrounding environment and further use the paper based sea chart to a larger extent than the novice drivers

An increased response to experimental muscle pain is related to psychological status in women with chronic non-traumatic neck-shoulder pain

<p>Abstract</p> <p>Background</p> <p>Neck-shoulder pain conditions, e.g., chronic trapezius myalgia, have been associated with sensory disturbances such as increased sensitivity to experimentally induced pain. This study investigated pain sensitivity in terms of bilateral pressure pain thresholds over the trapezius and tibialis anterior muscles and pain responses after a unilateral hypertonic saline infusion into the right legs tibialis anterior muscle and related those parameters to intensity and area size of the clinical pain and to psychological factors (sleeping problems, depression, anxiety, catastrophizing and fear-avoidance).</p> <p>Methods</p> <p>Nineteen women with chronic non-traumatic neck-shoulder pain but without simultaneous anatomically widespread clinical pain (NSP) and 30 age-matched pain-free female control subjects (CON) participated in the study.</p> <p>Results</p> <p>NSP had lower pressure pain thresholds over the trapezius and over the tibialis anterior muscles and experienced hypertonic saline-evoked pain in the tibialis anterior muscle to be significantly more intense and locally more widespread than CON. More intense symptoms of anxiety and depression together with a higher disability level were associated with increased pain responses to experimental pain induction and a larger area size of the clinical neck-shoulder pain at its worst.</p> <p>Conclusion</p> <p>These results indicate that central mechanisms e.g., central sensitization and altered descending control, are involved in chronic neck-shoulder pain since sensory hypersensitivity was found in areas distant to the site of clinical pain. Psychological status was found to interact with the perception, intensity, duration and distribution of induced pain (hypertonic saline) together with the spreading of clinical pain. The duration and intensity of pain correlated negatively with pressure pain thresholds.</p

Could sound be used as a strategy for reducing symptoms of perceived motion sickness?

<p>Abstract</p> <p>Background</p> <p>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.</p> <p>Methods</p> <p>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.</p> <p>Results</p> <p>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 non-positioned sound condition compared with sound horizon, indicating that the subjects used more time to fixate and, hence, assumingly made fewer saccades.</p> <p>Conclusion</p> <p>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.</p

Physiological responses to low-force work and psychosocial stress in women with chronic trapezius myalgia

<p>Abstract</p> <p>Background</p> <p>Repetitive and stressful work tasks have been linked to the development of pain in the trapezius muscle, although the underlying mechanisms still remain unclear. In earlier studies, it has been hypothesized that chronic muscle pain conditions are associated with imbalance in the autonomic nervous system, predominantly expressed as an increased sympathetic activity. This study investigates whether women with chronic trapezius myalgia show higher muscle activity and increased sympathetic tone at baseline and during repetitive low-force work and psychosocial stress, compared with pain-free controls.</p> <p>Methods</p> <p>Eighteen women with chronic trapezius myalgia (MYA) and 30 healthy female controls (CON) were studied during baseline rest, 100 min of repetitive low-force work, 20 min of psychosocial stress (Trier Social Stress Test, TSST), and 80 min recovery. The subjects rated their pain intensity, stress and energy level every 20 min throughout the experiment. Muscle activity was measured by surface electromyography in the trapezius muscle (EMGtrap) and deltoid muscle (EMGdelt). Autonomic reactivity was measured through heart rate (HR), skin conductance (SCL), blood pressure (MAP) and respiration rate (Resp).</p> <p>Results</p> <p>At baseline, EMGtrap, stress ratings, and HR were higher in MYA than in CON. Energy ratings, EMGdelt, SCL, MAP and Resp were, however, similar in the two groups. Significant main group effects were found for pain intensity, stress ratings and EMGtrap. Deltoid muscle activity and autonomic responses were almost identical in MYA and CON during work, stress and recovery. In MYA only, pain intensity and stress ratings increased towards the end of the repetitive work.</p> <p>Conclusion</p> <p>We found increased muscle activity during uninstructed rest in the painful muscle of a group of women with trapezius myalgia. The present study could not confirm the hypothesis that chronic trapezius myalgia is associated with increased sympathetic activity. The suggestion of autonomic imbalance in patients with chronic local or regional musculoskeletal pain needs to be further investigated.</p

I feel terrible! Can you measure that? : Exploring psychophysiological stress responses and their interactions with performance, subjective reports and health status

Despite recent research advances, there are still several common medical conditions whose underlying mechanisms are poorly understood. In conditions with few or diffuse physical findings, it can be difficult to diagnose and determine the state of the condition and its effects on working ability or performance, and the health care practitioners have to rely on the patient’s self-reports. Identification of objective measurements that are sensitive enough to aid in diagnosis or determination of the state of these conditions would thus be valuable. Psychophysiological measurements are generally non-invasive and have the potential to serve as such diagnostic or prognostic tools. In this thesis, psychophysiological reactions to different stressors were recorded in two selected medical conditions; namely motion sickness and chronic trapezius myalgia (musculoskeletal pain). These subjective conditions are unpleasant, unwanted and apparently serve no survival purpose. It is therefore important to elucidate any physical findings associated with them to, eventually, find new means to prevent the development of these conditions or to ameliorate symptoms. The overall aim of the thesis was to explore the development of psychophysiological responses to stressors in relation to performance and subjective reports in healthy individuals and in women with chronic trapezius myalgia. More in detail, the purpose was to identify psychophysiological responses that could provide information about the mechanisms behind, or serve as candidates for characterization of motion sickness and chronic trapezius myalgia, respectively. Responses to motion sickness, triggered by optokinetic stimulation, were studied in healthy individuals, whereas responses to repetitive low-force work and psychosocial stress were studied in women with chronic trapezius myalgia and in pain-free controls. In both medical conditions, the psychophysiological responses were accompanied by subjective reports. The effects of motion sickness on two different aspects of memory performance were tested during exposure to optokinetic stimulation. In the studies of chronic trapezius myalgia, psychophysiological responses were also related to health status, i.e., being a patient or a pain-free control and measurements of pain intensity, psychological symptoms, sleep-related problems and quality of life. The psychophysiological responses to optokinetic stimulation were inconclusive. Moderate levels of motion sickness did not affect memory performance, whereas decreased short term memory performance was seen in subjects reporting high levels of motion sickness. The autonomic responses and stress hormone secretion in response to low-force repetitive work and psychosocial stress in the chronic trapezius myalgia group were similar to those of the pain-free controls. However, muscle activity in the trapezius muscle was generally higher in the chronic trapezius myalgia group. There were indications of negative psychological states being related to a slower response and lower circadian variations of stress hormone secretion. With the present methods, it was possible to measure general stress responses but none of the measurements showed sufficient specificity to serve as predictors or indicators of motion sickness and chronic musculoskeletal pain, respectively. Summarizing, I cannot objectively measure how you feel; I still have to rely on your description of your condition

Evaluation of fatigue warning system in buses

Tidigare studier har visat att det är vanligt att bussförare i kollektivtrafik får kämpa för att hålla sig vakna flera gånger i månaden. Det finns i dagsläget tekniska system för att detektera trötthet hos förare men hur denna typ av system påverkar och uppfattas av bussförare är inte känt. Syftet med studien var att utvärdera effekten av ett trötthetsvarningssystem i långfärdsbussar. Studien omfattar två delstudier; en enkätstudie och en utvärdering av trötthetsvarningssystemet med bussförare på väg. Enkätstudien visade att de faktorer som upplevs som mest tröttande var att köra på natten, oregelbundna arbets- och sovtider och delade arbetspass/lång tid sedan rast. Det var 29% av förarna som uppgav att de behövde kämpa för att hålla sig vakna när de kör buss 2-4 ggr/ månad eller oftare. Datainsamlingen på väg visade att självskattad sömnighet var något lägre under körningar med trötthetsvarningssystemet aktivt. Trötthetsvarningssystemets loggar av trötthetshändelser samt förarnas rapporter av varningar som tagits emot stämde inte överens med deras upplevda trötthet. Förarna var överlag positiva till trötthetsvarningssystemet men lyfte fram att systemet behöver bli mer tillförlitligt.Previous studies have shown that it is common for bus drivers in public transport to struggle to stay awake several times a month. Several systems for detecting fatigue in drivers are currently available, but how these types of systems affect and are perceived by bus drivers is not known. The purpose of the study was to evaluate a fatigue warning system for use in long-distance buses. The study comprises two sub-studies; a survey and an on-road evaluation of the fatigue warning system. The survey showed that the factors that were considered the most tiring were driving at night, irregular working and sleeping hours and spread-over shifts/long time since a break. 29% of the drivers stated that they had to fight to stay awake when driving a bus 2–4 times/month or more. The on-road study showed that self-rated sleepiness was slightly lower when the fatigue warning system was active. The logs of fatigue events from the fatigue warning system and the drivers' reports of received warnings did not match their perceived fatigue. The drivers were generally positive about the fatigue warning system but emphasized that the system needs to be more reliable

Evaluation of fatigue warning system in buses

Tidigare studier har visat att det är vanligt att bussförare i kollektivtrafik får kämpa för att hålla sig vakna flera gånger i månaden. Det finns i dagsläget tekniska system för att detektera trötthet hos förare men hur denna typ av system påverkar och uppfattas av bussförare är inte känt. Syftet med studien var att utvärdera effekten av ett trötthetsvarningssystem i långfärdsbussar. Studien omfattar två delstudier; en enkätstudie och en utvärdering av trötthetsvarningssystemet med bussförare på väg. Enkätstudien visade att de faktorer som upplevs som mest tröttande var att köra på natten, oregelbundna arbets- och sovtider och delade arbetspass/lång tid sedan rast. Det var 29% av förarna som uppgav att de behövde kämpa för att hålla sig vakna när de kör buss 2-4 ggr/ månad eller oftare. Datainsamlingen på väg visade att självskattad sömnighet var något lägre under körningar med trötthetsvarningssystemet aktivt. Trötthetsvarningssystemets loggar av trötthetshändelser samt förarnas rapporter av varningar som tagits emot stämde inte överens med deras upplevda trötthet. Förarna var överlag positiva till trötthetsvarningssystemet men lyfte fram att systemet behöver bli mer tillförlitligt.Previous studies have shown that it is common for bus drivers in public transport to struggle to stay awake several times a month. Several systems for detecting fatigue in drivers are currently available, but how these types of systems affect and are perceived by bus drivers is not known. The purpose of the study was to evaluate a fatigue warning system for use in long-distance buses. The study comprises two sub-studies; a survey and an on-road evaluation of the fatigue warning system. The survey showed that the factors that were considered the most tiring were driving at night, irregular working and sleeping hours and spread-over shifts/long time since a break. 29% of the drivers stated that they had to fight to stay awake when driving a bus 2–4 times/month or more. The on-road study showed that self-rated sleepiness was slightly lower when the fatigue warning system was active. The logs of fatigue events from the fatigue warning system and the drivers' reports of received warnings did not match their perceived fatigue. The drivers were generally positive about the fatigue warning system but emphasized that the system needs to be more reliable