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Maximum voluntary hand grip torque for circular electrical connectors
people more familiar with use of the product will tend to read, comply with and recall the warning less than those less familiar. Also, people more confident with the use of the product will tend to read and comply less than those less confident. Type of warning label showed no effect. However, in all conditions with a warning label, an average of 25"5% complied with the warning (range 12"5"- 50%), and without a warning label no one took precautionary action consistent with the warning message. The findings support the contention that the use of conspicuously designed and placed warning labels on products will influence people to behave cautiously. 21.1.12 (113118)
Viscusi, W.K., and Magat, W.A. Learning about risk. Consumer and worker responses to hazard information. Harvard Univ Press, Cambridge, Mass, 1987, 197 pp, 83 refs. How do people decide whether or not to take chances with their health and safety? Do they pay attention to warnings about hazardous products used at home or on the j o b ? What is the best way to present this information? These questions are becoming increasingly important as direct government regulation is replaced by programmes to educate workers and consumers about risk. Information itself is becoming a regulatory device, but until now little has been known about its use and effectiveness. This b o o k offers important new evidence on how people • process information about risk and how they make choices under uncertainty. Drawing on work in a variety of disciplines - economics, decision science, marketing and psychology - as well as on original survey data, the authors take a close look at one type of risk information: the labelling of hazardous products and chemicals. They use the word labelling to mean all the tangible ways in which information is transmitted, including not merely warnings on bottles and cans but also leaflets and brochures, signs in the workplace, and store displays. The authors surveyed hundreds of consumers and chemical workers to explore a range of issues - the accuracy and appropriateness of people's risk assessments, the types of precautions they take, the values they attach to these measures, the wages they expect for performing risky jobs, and the relationship between the precaution taken and the content, wording and format of the warning.
Mestre, D. Visual control of displacement at slow speeds. Human Factors, 1988, 30.6, 6 6 3 - 6 7 5 , 29 refs.
Applied Ergonomics
21.t.14 (113209)
Mital, A., and Wang, L.W. Effects on load handling of restricted and unrestricted shelf opening clearances. Ergonomics, 1989, 32.1, 3 9 - 4 9 , 20 refs. Changes in psychophysical lifting capacity with reductions in shelf opening clearances were experimentally determined. Three levels of shelf opening clearances were studied: unrestricted shelf opening clearance, loose shelf opening clearance (a clearance of 15 mm between the box width and the shelf opening), and tight shelf opening clearance (a clearance of 3 mm between the box width and the shelf opening). Two levels of lifting frequency ( 1 and 4 lifts/min) and two lifting heights (floor to 0"81 m and 0.81 m to 1-52 m) were included. The metabolic energy expenditure rates and heart rates of the subjects (eight males and eight females) at psychophysically acceptable weights of lift were also recorded to assess the physiological burden. The results indicated a decline in the psychophysical lifting capacity of the subjects as the shelf opening clearance became narrower. The decline in psychophysical capacity, compared with unrestricted shelf opening clearance for males was 9% when the shelf opening clearance narrowed down to 3 mm. F o r females, the corresponding declines were approximately 10% and 4%. The effects of lifting frequency and height of lift were found to be consistent with previous findings. 21.1.15 (113221)
Gilbert, B.G., Hahn, H.A., Gilmore, W.E., and Schurman, D.L.
21.1.13 (113193)
78
Harbour navigation was simulated on a computer-driven real-time system. Subjects' ability to keep a virtual vehicle within spatial boundaries was investigated in a situation in which the apparent transformations of the visual scene could only be perceived as successive perspective views of the navigation area. In two experiments, subjects' performance was measured as a function of the visual information available. Results indicate that providing dynamic visual cues indicating the rotational movement of the vehicle (experiment 1) or the spatial properties of its trajectory (experiment 2) results in improved performance. They suggest how fundamental the role of motion perceptions is in vehicle guidance, and bring up its possible implications for the ergonomics of displacement control at slow speeds.
Thumbs up: A n t h r o p o m e t r y of the first digit. Human Factors, 1988, 30.6, 7 4 7 - 7 5 0 , 2 refs.
March 1990
A need was identified for data concerned with maximum possible and maximum comfortable angular displacement of the thumb. These measures, along with thumb reach data, were collected from a sample of 105 subjects. It was found that thumb reach was not correlated with either maximum or most comfortable degree of angular displacement. In addition, angular displacement was not correlated with age. Design guidelines for angular displacement of the thumb are provided. 21.1.16 (113224)
Roebuck, J., Smith, K., and Raggio, L. Forecasting crew anthropometry for shuttle and space station. In: Riding the Wave of Innovation. Proc Human Factors Soc 32nd Ann Meeting, Anaheim, California, 2 4 - 2 8 Oct, 1988. The Human Factors Soc, Santa Monica, California, Vol 1, 1988, pp 3 5 - 3 9 , 14 refs. Habitation module and Crew Emergency Rescue Vehicle (CERV) designs for the International Space Station to be built by the United States are expected to accommodate a wide range of persons, according to body dimensions predicted for the year 2000. This prediction was aided by the opportunity, which arose in 1985, to check actual Space Shuttle male crew anthropometry, particularly stature, against predictions made circa 1973 and by recently acquired Japanese data. Revised hypotheses discussed herein have been accepted by an A n t h r o p o m e t r y Working Group as the bases for developing anthropomerry requirements that appear in the Man-Systems Integration Standard (NASA-STD-3000), published in 1987. Pleas are made for further research in civilian anthropometry and wider use of anthropometric forecasting. 21.1.17 (113227)
Adams, S.K., and Peterson, P.J. Maximum voluntary hand grip torque for circular electrical connectors. Human Factors, 1988, 3 0 . 6 , 7 3 3 - 7 4 5 , 10 refs. A study was performed to determine maximum hand grip torque that can be exerted when tightening or loosening circular electrical connectors. A static, sustained three-second exertion was used as the strength criterior~. Torque was applied to simulated connector rings and was measured by means of a single bridge torsional load cell. Other variables tested included the type of grip employed, orientation of the connector, use of work gloves and chemical defence gloves, height of the connectors, and direction or rotation. Hand grip torque strength was found to be directly related to
connector diameter, with similar strength patterns exhibited for tightening and loosening. Higher torque was exerted when the connectors were on the subject's right side. The use of gloves resulted in higher torque in most situations. Connector height and direction of rotation had little effect on torque strength. 21.1.18 (113232) Imrhan, S.N. A comparison of the results of recent studies in wrist-twisting strength. In: Trends in Ergonomics/Human Factors V, F. Aghazadeh (Ed). North-Holland, Amsterdam, 1988, pp 2 3 5 - 2 3 9 , 7 refs. Seven relatively recent studies on wrist-twisting strength have been compared. The studies reveal that, for circular screw-type container lids, wrist-twisting torque depends mainly on the diameter and surface finish of the lids. The diameter and height influences the type of grip used, and hence torque. Knurls and threads on commercial lids have been ineffective for torque generation, except for very large-diameter lids. Enough data does not exist to make strong conclusions concerning relationships between torque and lid height, body posture and different age groups of the population. 21.1.19 (113246)
Oman, P.W., Gomes, C.S., Rains, K., and Morandi, M. Posture and VDU operator satisfaction.
SIGCHIBull, 1989, 20.3, 5 2 - 5 7 , 19 refs. Few studies have looked at how workers adapt their posture, to fit their work environment, and virtually none has compared this adaptation with reports of user satisfaction. This study focused on the relationship between users' size and posture, and the phsyical attributes of VDU workplaces. A survey on VDU operator satisfaction was conducted and compared with results from a controlled study on posture transitions occurring at VDU workplaces. Results demonstrate that workers adapt their posture to fit their work environment, rather than adjust their workstation to permit an optimal posture that may increase productivity. These results support the recommendations for comprehensive worker training on the ergonomics benefits of workstation adjustment and suggest the need for dynamically adjustable workstation components that periodically conform to the worker's posture. 21.1.20 (113321)
James, A. Perceptions of stress in British ambulance personnel. Work and Stress, 1988, 2 . 4 , 3 1 9 326, 12refs.
This paper reports upon an investigative study of stress in the ambulance service. The aims of the research were in part methodological and in part substantive. Methodologically, the study sought to validate as measurable constructs the perceptions of sources of stress reported by ambulance staff in response to questionnaire items. Substantively, it sought to identify these possible sources of stress and to measure the relationship between their perceived importance and such moderating variables as personality charactersitics, length of service, and urban or rural locations of operation and rank. Both aspects of the study are reported. 21.1.21 (113323)
Simmel, E.C., Cerkovnik, M., and McCarthy, J.E. Sources of stress affecting pilot judgement. Aviation, Space & Environ Med, 1989, 60.1, 5 3 - 5 5 , 7 refs. The initial stages of the research on the effects of the over-assessment or under-assessment of the consequences of non-routine events (a potentially important factor in decision-making by pilots) is described. Critical difficulties in the measurement of life stress are discussed and a partial solution is suggested in the form of the Life Events Questionnaire (LEQ), an instrument on which individuals report the nature of stressful events, when they happened, and how much they concern them at the time of testing. The results show that the tendency to over-assess or underassess the consequences of non-routine events is consistent within individuals, but is unaffected by life stress levels on the artificial air traffic control simulation used. Analysis of LEQ results showed that high-stress subjects had much higher chronic than acute stress scores (p < 0-001), although the chronic and acute scores were virtually identical for low-stress subjects.
a readily detectible alphanumeric change; complex events (detection of two aircraft at the same altitude on the same flight path) required considerable information processing for detection. Behaviours following detection of each type of event enabled acquisition of data on short-term memory, decision time and errors, procedural errors and motor movement time. Time to detect aircraft at the same altitude was found to increase significantly over the 2 h as did failures to detect these events. Detection time for the simple type of event showed no evidence of impairment, nor was any impairment found for any of the other task behaviours that were measured. The results are discussed with reference to previous studies which suggest that the extent to which attentional decline impairs complex monitoring performance may be related to the amount of information processing required for event detection.
Information
presentation and communication 21.1.23 (113346)
Kaster, J., and Widdel, H. Interactive colour coding of digital maps on electronic displays. Displays Technol and Applications, 1989, 10.1, 1 2 - 1 6 , 12 refs. An interactive method is used to define parameters of colour codes on CRT displays and the applications of this method given for the design of digital maps on electronic displays. The present approach is based on the concept of the photo-colorimetric space, which offers the opportunity for the formal description of CRT characteristics. An experiment using this method for colouring electronic map displays is described and the results are presented. 21.1.24 (113347)
Dewar, R. 21.1.22 (113329) Effects of high visual taskload on the behaviours involved in complex monitoring. Ergonomics, 1989, 32.1, 2 7 - 3 8 , 12 refs
Criteria for the design and evaluation of traffic sign symbols. In: Traffic Control Devices 1988. Transportation Research Board, Washington, DC, Transportation Research Record 1160, 1988, pp 1 - 6 , 15 refs.
A simulated air traffic control task was used to study the effects of prolonged monitoring on some of the behaviours (complex discriminations, interpretations, decision, memory for actions taken) frequently associated with operational monitoring tasks, but seldom examined in laboratory vigilance studies. Forty-eight subjects performed the monitoring task under relatively high taskload conditions for 2 h. Two types of critical events were employed. Simple events consisted of
Several criteria for traffic sign symbols were examined through a questionnaire survey that allowed determination of the importance, or weighting, that should be assigned to each symbol in the design and evaluation of signs. The survey sample included traffic sign experts (members of national traffic control device committees) and practising traffic engineers from Australia, New Zealand, Canada and the United States. Separate ratings were assembled for symbols in general and for warning,
Thackray, R.I., and Touchstone, R.M.
Applied Ergonomics
March 1990
79
Viscusi, W.K., and Magat, W.A. Learning about risk. Consumer and worker responses to hazard information. Harvard Univ Press, Cambridge, Mass, 1987, 197 pp, 83 refs. How do people decide whether or not to take chances with their health and safety? Do they pay attention to warnings about hazardous products used at home or on the j o b ? What is the best way to present this information? These questions are becoming increasingly important as direct government regulation is replaced by programmes to educate workers and consumers about risk. Information itself is becoming a regulatory device, but until now little has been known about its use and effectiveness. This b o o k offers important new evidence on how people • process information about risk and how they make choices under uncertainty. Drawing on work in a variety of disciplines - economics, decision science, marketing and psychology - as well as on original survey data, the authors take a close look at one type of risk information: the labelling of hazardous products and chemicals. They use the word labelling to mean all the tangible ways in which information is transmitted, including not merely warnings on bottles and cans but also leaflets and brochures, signs in the workplace, and store displays. The authors surveyed hundreds of consumers and chemical workers to explore a range of issues - the accuracy and appropriateness of people's risk assessments, the types of precautions they take, the values they attach to these measures, the wages they expect for performing risky jobs, and the relationship between the precaution taken and the content, wording and format of the warning.
Mestre, D. Visual control of displacement at slow speeds. Human Factors, 1988, 30.6, 6 6 3 - 6 7 5 , 29 refs.
Applied Ergonomics
21.t.14 (113209)
Mital, A., and Wang, L.W. Effects on load handling of restricted and unrestricted shelf opening clearances. Ergonomics, 1989, 32.1, 3 9 - 4 9 , 20 refs. Changes in psychophysical lifting capacity with reductions in shelf opening clearances were experimentally determined. Three levels of shelf opening clearances were studied: unrestricted shelf opening clearance, loose shelf opening clearance (a clearance of 15 mm between the box width and the shelf opening), and tight shelf opening clearance (a clearance of 3 mm between the box width and the shelf opening). Two levels of lifting frequency ( 1 and 4 lifts/min) and two lifting heights (floor to 0"81 m and 0.81 m to 1-52 m) were included. The metabolic energy expenditure rates and heart rates of the subjects (eight males and eight females) at psychophysically acceptable weights of lift were also recorded to assess the physiological burden. The results indicated a decline in the psychophysical lifting capacity of the subjects as the shelf opening clearance became narrower. The decline in psychophysical capacity, compared with unrestricted shelf opening clearance for males was 9% when the shelf opening clearance narrowed down to 3 mm. F o r females, the corresponding declines were approximately 10% and 4%. The effects of lifting frequency and height of lift were found to be consistent with previous findings. 21.1.15 (113221)
Gilbert, B.G., Hahn, H.A., Gilmore, W.E., and Schurman, D.L.
21.1.13 (113193)
78
Harbour navigation was simulated on a computer-driven real-time system. Subjects' ability to keep a virtual vehicle within spatial boundaries was investigated in a situation in which the apparent transformations of the visual scene could only be perceived as successive perspective views of the navigation area. In two experiments, subjects' performance was measured as a function of the visual information available. Results indicate that providing dynamic visual cues indicating the rotational movement of the vehicle (experiment 1) or the spatial properties of its trajectory (experiment 2) results in improved performance. They suggest how fundamental the role of motion perceptions is in vehicle guidance, and bring up its possible implications for the ergonomics of displacement control at slow speeds.
Thumbs up: A n t h r o p o m e t r y of the first digit. Human Factors, 1988, 30.6, 7 4 7 - 7 5 0 , 2 refs.
March 1990
A need was identified for data concerned with maximum possible and maximum comfortable angular displacement of the thumb. These measures, along with thumb reach data, were collected from a sample of 105 subjects. It was found that thumb reach was not correlated with either maximum or most comfortable degree of angular displacement. In addition, angular displacement was not correlated with age. Design guidelines for angular displacement of the thumb are provided. 21.1.16 (113224)
Roebuck, J., Smith, K., and Raggio, L. Forecasting crew anthropometry for shuttle and space station. In: Riding the Wave of Innovation. Proc Human Factors Soc 32nd Ann Meeting, Anaheim, California, 2 4 - 2 8 Oct, 1988. The Human Factors Soc, Santa Monica, California, Vol 1, 1988, pp 3 5 - 3 9 , 14 refs. Habitation module and Crew Emergency Rescue Vehicle (CERV) designs for the International Space Station to be built by the United States are expected to accommodate a wide range of persons, according to body dimensions predicted for the year 2000. This prediction was aided by the opportunity, which arose in 1985, to check actual Space Shuttle male crew anthropometry, particularly stature, against predictions made circa 1973 and by recently acquired Japanese data. Revised hypotheses discussed herein have been accepted by an A n t h r o p o m e t r y Working Group as the bases for developing anthropomerry requirements that appear in the Man-Systems Integration Standard (NASA-STD-3000), published in 1987. Pleas are made for further research in civilian anthropometry and wider use of anthropometric forecasting. 21.1.17 (113227)
Adams, S.K., and Peterson, P.J. Maximum voluntary hand grip torque for circular electrical connectors. Human Factors, 1988, 3 0 . 6 , 7 3 3 - 7 4 5 , 10 refs. A study was performed to determine maximum hand grip torque that can be exerted when tightening or loosening circular electrical connectors. A static, sustained three-second exertion was used as the strength criterior~. Torque was applied to simulated connector rings and was measured by means of a single bridge torsional load cell. Other variables tested included the type of grip employed, orientation of the connector, use of work gloves and chemical defence gloves, height of the connectors, and direction or rotation. Hand grip torque strength was found to be directly related to
connector diameter, with similar strength patterns exhibited for tightening and loosening. Higher torque was exerted when the connectors were on the subject's right side. The use of gloves resulted in higher torque in most situations. Connector height and direction of rotation had little effect on torque strength. 21.1.18 (113232) Imrhan, S.N. A comparison of the results of recent studies in wrist-twisting strength. In: Trends in Ergonomics/Human Factors V, F. Aghazadeh (Ed). North-Holland, Amsterdam, 1988, pp 2 3 5 - 2 3 9 , 7 refs. Seven relatively recent studies on wrist-twisting strength have been compared. The studies reveal that, for circular screw-type container lids, wrist-twisting torque depends mainly on the diameter and surface finish of the lids. The diameter and height influences the type of grip used, and hence torque. Knurls and threads on commercial lids have been ineffective for torque generation, except for very large-diameter lids. Enough data does not exist to make strong conclusions concerning relationships between torque and lid height, body posture and different age groups of the population. 21.1.19 (113246)
Oman, P.W., Gomes, C.S., Rains, K., and Morandi, M. Posture and VDU operator satisfaction.
SIGCHIBull, 1989, 20.3, 5 2 - 5 7 , 19 refs. Few studies have looked at how workers adapt their posture, to fit their work environment, and virtually none has compared this adaptation with reports of user satisfaction. This study focused on the relationship between users' size and posture, and the phsyical attributes of VDU workplaces. A survey on VDU operator satisfaction was conducted and compared with results from a controlled study on posture transitions occurring at VDU workplaces. Results demonstrate that workers adapt their posture to fit their work environment, rather than adjust their workstation to permit an optimal posture that may increase productivity. These results support the recommendations for comprehensive worker training on the ergonomics benefits of workstation adjustment and suggest the need for dynamically adjustable workstation components that periodically conform to the worker's posture. 21.1.20 (113321)
James, A. Perceptions of stress in British ambulance personnel. Work and Stress, 1988, 2 . 4 , 3 1 9 326, 12refs.
This paper reports upon an investigative study of stress in the ambulance service. The aims of the research were in part methodological and in part substantive. Methodologically, the study sought to validate as measurable constructs the perceptions of sources of stress reported by ambulance staff in response to questionnaire items. Substantively, it sought to identify these possible sources of stress and to measure the relationship between their perceived importance and such moderating variables as personality charactersitics, length of service, and urban or rural locations of operation and rank. Both aspects of the study are reported. 21.1.21 (113323)
Simmel, E.C., Cerkovnik, M., and McCarthy, J.E. Sources of stress affecting pilot judgement. Aviation, Space & Environ Med, 1989, 60.1, 5 3 - 5 5 , 7 refs. The initial stages of the research on the effects of the over-assessment or under-assessment of the consequences of non-routine events (a potentially important factor in decision-making by pilots) is described. Critical difficulties in the measurement of life stress are discussed and a partial solution is suggested in the form of the Life Events Questionnaire (LEQ), an instrument on which individuals report the nature of stressful events, when they happened, and how much they concern them at the time of testing. The results show that the tendency to over-assess or underassess the consequences of non-routine events is consistent within individuals, but is unaffected by life stress levels on the artificial air traffic control simulation used. Analysis of LEQ results showed that high-stress subjects had much higher chronic than acute stress scores (p < 0-001), although the chronic and acute scores were virtually identical for low-stress subjects.
a readily detectible alphanumeric change; complex events (detection of two aircraft at the same altitude on the same flight path) required considerable information processing for detection. Behaviours following detection of each type of event enabled acquisition of data on short-term memory, decision time and errors, procedural errors and motor movement time. Time to detect aircraft at the same altitude was found to increase significantly over the 2 h as did failures to detect these events. Detection time for the simple type of event showed no evidence of impairment, nor was any impairment found for any of the other task behaviours that were measured. The results are discussed with reference to previous studies which suggest that the extent to which attentional decline impairs complex monitoring performance may be related to the amount of information processing required for event detection.
Information
presentation and communication 21.1.23 (113346)
Kaster, J., and Widdel, H. Interactive colour coding of digital maps on electronic displays. Displays Technol and Applications, 1989, 10.1, 1 2 - 1 6 , 12 refs. An interactive method is used to define parameters of colour codes on CRT displays and the applications of this method given for the design of digital maps on electronic displays. The present approach is based on the concept of the photo-colorimetric space, which offers the opportunity for the formal description of CRT characteristics. An experiment using this method for colouring electronic map displays is described and the results are presented. 21.1.24 (113347)
Dewar, R. 21.1.22 (113329) Effects of high visual taskload on the behaviours involved in complex monitoring. Ergonomics, 1989, 32.1, 2 7 - 3 8 , 12 refs
Criteria for the design and evaluation of traffic sign symbols. In: Traffic Control Devices 1988. Transportation Research Board, Washington, DC, Transportation Research Record 1160, 1988, pp 1 - 6 , 15 refs.
A simulated air traffic control task was used to study the effects of prolonged monitoring on some of the behaviours (complex discriminations, interpretations, decision, memory for actions taken) frequently associated with operational monitoring tasks, but seldom examined in laboratory vigilance studies. Forty-eight subjects performed the monitoring task under relatively high taskload conditions for 2 h. Two types of critical events were employed. Simple events consisted of
Several criteria for traffic sign symbols were examined through a questionnaire survey that allowed determination of the importance, or weighting, that should be assigned to each symbol in the design and evaluation of signs. The survey sample included traffic sign experts (members of national traffic control device committees) and practising traffic engineers from Australia, New Zealand, Canada and the United States. Separate ratings were assembled for symbols in general and for warning,
Thackray, R.I., and Touchstone, R.M.
Applied Ergonomics
March 1990
79