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693 Multivariate workload evaluation — An integration of subjective and physiological parameters
262
Abstracts
/International
Journal
we have found that the magnitude of the aftereffects decreases with the distance from the positions that experienced the force perturbations. In addition, we also fmd that older subjects seem to learn force compensation less quickly than younger people do and that they show aftereffects or a longer time. Interestingly few of our subjects have had a big latency in learning the baseline of the task, that is reaching the target within the allotted time, some not learning it at all. These few subjects had no diagnosable neurological or orthopedic impairments. Further work is needed to evaluate the importance of this intriguing finding.
693 MULTIVARIATE WORKLOAD EVALUATION - AN INTEGRATION OF SUBJECTIVE AND PHYSIOLOGICAL PARAMETERS
S. Miyake* Univ. of Occupational and Environmental Health, Iseigaoka, Yahatanishiku, Kitakyushu 8078555 Japan
l-l
A workload evaluation index composed of psychophysiological and subjective measures was investigated. Three different physiological measures, i.e., the heart rate variability (ln(LF/HF)) as a cardiovascular parametfi, photoelectric plethysmogram amplitude as a peripheral blood vessel activity parameter and perspiration as a non-vascular ANS parameter were recorded from sixteen male subjects during complete experimental blocks, including before and after task rest periods. The subjective workload scores were-also obtained by means of the National Aeronautics and Space Administration Task Load Index (NASA-T%). The mental tasks performed were a wood piece puzzle (PZ), two-dimensional compentatoty tracking tasks with three levels of difficulty (‘ITH, TT md TTL, the third letter of each stands for the level of liff~culty, i.e., H is for High, M is for Medium and L is for ow) and numerical logical tasks (NLH, NLM and NLL). ‘hysiological workload evaluation (PWE) scores were calcuated by means of the principal component analysis (PCA) of hree physiological parameters mentioned above. Higher corelation coefficients were found between PWE scores and LX-MTE scores, which were the average of Mental Demand MD), Temporal Demand (TD) and Effort (EF) subscales of IAS TLX rather than between PWE scores and WWL weighted Workload) by all six subscales. Furthermore, the WE and TLX-MTE scores showed significant differences etween PZ and TIH, although there was no significant ifferences between them in regards to WWL scores. These :sults suggest that OP (Own Performance) and PD (Physical #emand) subsoales in NASA-TLX do not contribute much to he physiological responses recorded during the task per‘rming periods. The main purpose of the study was not to find physiological dices which have high correlation with subjective scales, but
of Psychophysiology300
(1998)
95-271
was to integrate subjective measures and physiological parameters and to evaluate workload multivariately. The three physiological parameters and TLX-MTE scores were analyzed by PCA and the first principal component scores were obtained as multivariate workload evaluation (MWE) scores. All parameters used in this study were standardized in each subject. Therefore, MWE scores are relative parameters within subjects and the method used here was based on the response of each individual. This means th the weight coefficients (factor loading coefficients) of equations used to calculate the MWE scores were different between subjects. This individual-based multivariate workload evaluation method seems to be useful for the workload research.
694 DOES PARTIAL SLEEP DEPRIVATION HAVE AN EFFECT ON LOW VIGILANCE STATE OCCURRING WHILE DRIVING IN EARLY AFTERNOON? Alain Muzet*, Valerie Muzet, Joceline Roge, Thierry Pebayle CNRS-CEPA, 21 rue Becquerel, Strasbourg, 67087 France Seventeen young adults (9 males and 8 females) spent two nights in the laboratory. On the first night they were allowed to sleep from 23:00 to 07:OO while in the following night, sleep was possible only from 23:00 to 03:OO. On the subsequent early afternoons subjects drove a moving base driving simulator for two hours (from 1400 to 16:OO).The driving task was a monotonou@sdrive on an empty freeway and subjects were instructed to respect speed limits indicated on the road side and to stop at any time if needed. Electrophysiological recordings included 3 EEGs (F3, C3 and 01, referenced to A2), vertical and horizontal EOGs and heart rate. Before starting the drive subjects were recorded in the simulator for 5 mn eyes open and then for 5 mn eyes closed. Low vigilance state was scored according to occurrence of alpha and/or theta activities on, at least, two EEG leads simultaneously. Seconds spent in low vigilance state were cumulated for each oneminute period during the two-hour drive. ANOVA analysis showed no significant difference neither between sexes nor between the two conditions (with or without sleep deprivation). A marked effect due to time in driving was observed, the time spent in low vigilance state increasing significantly (p < 0.001) from the first half an hour to the following 30-mn periods. It appeared also that some subjects had clear increase in time spent in low vigilance state when driving after a reduced night of sleep, while others exhibited no such difference between the two conditions. Amount of alpha produced in the pre-drive test might help to distinguish between these two groups of subjects.
695 INDUCED ELECTRODERMAL ACTIVITY BEFORE AND AFTER REPEATED FLIGHTS AS A CHARACTERISTICS OF FATIGUE
Abstracts
/International
Journal
we have found that the magnitude of the aftereffects decreases with the distance from the positions that experienced the force perturbations. In addition, we also fmd that older subjects seem to learn force compensation less quickly than younger people do and that they show aftereffects or a longer time. Interestingly few of our subjects have had a big latency in learning the baseline of the task, that is reaching the target within the allotted time, some not learning it at all. These few subjects had no diagnosable neurological or orthopedic impairments. Further work is needed to evaluate the importance of this intriguing finding.
693 MULTIVARIATE WORKLOAD EVALUATION - AN INTEGRATION OF SUBJECTIVE AND PHYSIOLOGICAL PARAMETERS
S. Miyake* Univ. of Occupational and Environmental Health, Iseigaoka, Yahatanishiku, Kitakyushu 8078555 Japan
l-l
A workload evaluation index composed of psychophysiological and subjective measures was investigated. Three different physiological measures, i.e., the heart rate variability (ln(LF/HF)) as a cardiovascular parametfi, photoelectric plethysmogram amplitude as a peripheral blood vessel activity parameter and perspiration as a non-vascular ANS parameter were recorded from sixteen male subjects during complete experimental blocks, including before and after task rest periods. The subjective workload scores were-also obtained by means of the National Aeronautics and Space Administration Task Load Index (NASA-T%). The mental tasks performed were a wood piece puzzle (PZ), two-dimensional compentatoty tracking tasks with three levels of difficulty (‘ITH, TT md TTL, the third letter of each stands for the level of liff~culty, i.e., H is for High, M is for Medium and L is for ow) and numerical logical tasks (NLH, NLM and NLL). ‘hysiological workload evaluation (PWE) scores were calcuated by means of the principal component analysis (PCA) of hree physiological parameters mentioned above. Higher corelation coefficients were found between PWE scores and LX-MTE scores, which were the average of Mental Demand MD), Temporal Demand (TD) and Effort (EF) subscales of IAS TLX rather than between PWE scores and WWL weighted Workload) by all six subscales. Furthermore, the WE and TLX-MTE scores showed significant differences etween PZ and TIH, although there was no significant ifferences between them in regards to WWL scores. These :sults suggest that OP (Own Performance) and PD (Physical #emand) subsoales in NASA-TLX do not contribute much to he physiological responses recorded during the task per‘rming periods. The main purpose of the study was not to find physiological dices which have high correlation with subjective scales, but
of Psychophysiology300
(1998)
95-271
was to integrate subjective measures and physiological parameters and to evaluate workload multivariately. The three physiological parameters and TLX-MTE scores were analyzed by PCA and the first principal component scores were obtained as multivariate workload evaluation (MWE) scores. All parameters used in this study were standardized in each subject. Therefore, MWE scores are relative parameters within subjects and the method used here was based on the response of each individual. This means th the weight coefficients (factor loading coefficients) of equations used to calculate the MWE scores were different between subjects. This individual-based multivariate workload evaluation method seems to be useful for the workload research.
694 DOES PARTIAL SLEEP DEPRIVATION HAVE AN EFFECT ON LOW VIGILANCE STATE OCCURRING WHILE DRIVING IN EARLY AFTERNOON? Alain Muzet*, Valerie Muzet, Joceline Roge, Thierry Pebayle CNRS-CEPA, 21 rue Becquerel, Strasbourg, 67087 France Seventeen young adults (9 males and 8 females) spent two nights in the laboratory. On the first night they were allowed to sleep from 23:00 to 07:OO while in the following night, sleep was possible only from 23:00 to 03:OO. On the subsequent early afternoons subjects drove a moving base driving simulator for two hours (from 1400 to 16:OO).The driving task was a monotonou@sdrive on an empty freeway and subjects were instructed to respect speed limits indicated on the road side and to stop at any time if needed. Electrophysiological recordings included 3 EEGs (F3, C3 and 01, referenced to A2), vertical and horizontal EOGs and heart rate. Before starting the drive subjects were recorded in the simulator for 5 mn eyes open and then for 5 mn eyes closed. Low vigilance state was scored according to occurrence of alpha and/or theta activities on, at least, two EEG leads simultaneously. Seconds spent in low vigilance state were cumulated for each oneminute period during the two-hour drive. ANOVA analysis showed no significant difference neither between sexes nor between the two conditions (with or without sleep deprivation). A marked effect due to time in driving was observed, the time spent in low vigilance state increasing significantly (p < 0.001) from the first half an hour to the following 30-mn periods. It appeared also that some subjects had clear increase in time spent in low vigilance state when driving after a reduced night of sleep, while others exhibited no such difference between the two conditions. Amount of alpha produced in the pre-drive test might help to distinguish between these two groups of subjects.
695 INDUCED ELECTRODERMAL ACTIVITY BEFORE AND AFTER REPEATED FLIGHTS AS A CHARACTERISTICS OF FATIGUE