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Time: the Cinderella of man-machine interaction
22.3.5 (120153)
Whiting, J.F., and Horrigan, K.R. Forensic ergonomics. In: Ergonomics, Technology and Productivity, Proc 25th Ann Conf of the Ergonomics Soc of Australia, 2 6 - 2 9 Nov 1989. Ergonomics Soc o f Australia, Fortitude Valley, Queensland, 1989, pp 3 3 5 341, 12 refs. Increasing litigiousness in Australian society has led to an increase in the demand for expert witnesses to provide opinions on human factors before and during court processes. This paper presents some of the special requirements of such evidence and opinions as well as the necessary attributes of the experts themselves, the 'forensic ergonomists'.
H uman characteristics 22.3.6 (119560) Unema, P., and Rotti~, M. Differences in eye movements and mental workload between experienced and inexperienced motor-vehicle drivers. In: D. Brogan (Ed). Visual Search, Taylor & Francis, London, 1990, pp 1 9 3 - 2 0 2 , 11 refs. A great number of eye movement studies have pointed out that fixation duration is influenced by mental workload. The results are by no means ambiguous, however, with some studies reporting longer fixation times when task difficulty is increased, whilst others report shorter fixation times. In the present study it is argued that, within a theoretical framework based upon a combined cognitive stage model of information processing, most of these differences can be reconciled. The difference is thought to lie in the type of task that is being performed, and (more specifically) in the approximate mental state for performing that task. Thus, fixation duration and scanning behaviour may be indicative of the mental state of the subject. These hypotheses were tested in two field experiments with 20 city bus drivers in the city of Berlin, and 12 car drivers in Maastricht, The Netherlands. Both groups contained experienced and inexperienced drivers. F o r data analysis and interpretation purposes, the field of view was divided into seven areas of interest. The courses were divded into segments (77 for the Berlin experiments, and 124 for the Maastricht), grouped according to situational similarity (e g, right turns, left turns, straight lanes) representing different degrees of difficulty, and selected for further analysis. The relative importance of an area of interest varied with the situational demands, as indicated by the dwell times per area of interest, thus con-
Controlling a complex system requires the management of an enormous amount of information. This information is very often temporal in nature. Prediction, action, plan choice and co-ordinating the actions of several people all involve reasoning about time. Three temporal structures are confronted in man-machine interactions: machine, man and team. These temporal interactions need to be grasped in any analysis. In particular, they seem essential in a Human Reliability Analysis, as well as in an intelligent display design approach. An analysis of man-machine interactions in a complex dynamic environment, and particularly during a plant start-up situation, constitutes the basis of the concepts developed. The case study presented here shows how process plant operators face the time complexity o f a plant start-up. This peculiar situation offers a very vivid o p p o r t u n i t y to analyse the mechanisms o f temporal reasoning. In particular, mechanisms of time internatisation and temporal pattern matching have been found to be very helpful for temporal strategies. Some difficulties encountered by the operator in the estimation of temporal sequences, time duration and time of action have been analysed with regard to possible temporal errors.
performance of hypothetical cueing systems. These ranged from a 'perfect' system (i e, 100% hits, no misses and no false alarms), to a ' p o o r ' system (which cues 60% of the targets, misses the other 40%, and registers 33% false alarms). The remaining two systems were 'low risk' and 'high risk. The high-risk system cued all the targets, but also cued 33% false alarms. The observers were not informed about the criterion used in cued scenes. They were told only that the cueing system might cue some non-targets, and might miss some targets. The imagery was dynamic air-to-ground thermal scenes of farmland and villages. The targets were military vehicles. The cues were 'V' shapes placed above the object. Cueing began as soon as the object was visible, and followed the object continuously as it passed from the screen. The results show that the presence of cues can be beneficial to human search performance by reducing false designations, but there is no advantage in cueing all targets. There is an advantage in cueing only real targets (keeping cues to a minimum). Although all cueing systems obtained a higher or equal rate o f target designation from observers than uncued search, the difference was n o t significant. The greatest increase in designation rate was 14%. [t was found that significantly fewer false alarms were designated with three of the four cueing systems, compared with uncued search. The high-risk system produced as m a n y false alarm designations as uncued search. Also, different cueing systems resulted in significantly different designation strategies by the human observer: uncued targets were designated more than cued targets in some cases, while uncued targets were rarely designated in other cases. The results indicate that observer expectations about the reliability of the cueing system might be affected by the number of cues presented. Where a large number of cues is presented, more errors are expected, so more cued items are rejected and more uncued items are designated.
22.3.8 (119601) Car L K.T. An investigation into the effects o f a simulated thermal cueing aid upon air-to-ground search performance. In: D. Brogan (Ed). Visual search, Taylor & Francis, London, 1990, pp 3 6 1 - 3 7 0 , 21 refs.
22.3.9 (119602) Carver, E.M. Search o f imagery from airborne sensors - implications for selection of sensor and method of changing field-ofview. In: D. Brogan (Ed). Visual search, Taylor & Francis, London, 1990, pp 3 7 1 - 3 8 2 , 11 refs.
An experiment was carried out to make a preliminary assessment of the benefits to human search performance which can be gained from automatic cueing of target-like signatures in thermal imagery. F o u r different cueing criteria were used in simulating the
Reconnaissance systems are becoming increasingly complex, providing more and more information, and capabilities to the image interpreter. The overriding question is: Can the observer cope with the imagery that is presented to him? This
firming that the method of data reduction is useful, and prevents loss o f significant information. F i x a t i o n duration decreases with increasing situation complexity. Furthermore, fixations of extreme short duration occur less, with more experienced subjects. These data suggest that there exists a link between the control of fixations o f extreme short duration and the energetic state of the subject. 22.3.7 (119595)
Decortis, F., and De Keyser, V. Time: the Cinderella o f man-machine interaction. In: J. Ranta (Ed). Analysis, design and evaluation of man-machine systems 1988, Pergamon Press, Oxford, 1989, pp 6 5 - 7 0 , 14 refs.
Applied Ergonomics
June 1991
205
Whiting, J.F., and Horrigan, K.R. Forensic ergonomics. In: Ergonomics, Technology and Productivity, Proc 25th Ann Conf of the Ergonomics Soc of Australia, 2 6 - 2 9 Nov 1989. Ergonomics Soc o f Australia, Fortitude Valley, Queensland, 1989, pp 3 3 5 341, 12 refs. Increasing litigiousness in Australian society has led to an increase in the demand for expert witnesses to provide opinions on human factors before and during court processes. This paper presents some of the special requirements of such evidence and opinions as well as the necessary attributes of the experts themselves, the 'forensic ergonomists'.
H uman characteristics 22.3.6 (119560) Unema, P., and Rotti~, M. Differences in eye movements and mental workload between experienced and inexperienced motor-vehicle drivers. In: D. Brogan (Ed). Visual Search, Taylor & Francis, London, 1990, pp 1 9 3 - 2 0 2 , 11 refs. A great number of eye movement studies have pointed out that fixation duration is influenced by mental workload. The results are by no means ambiguous, however, with some studies reporting longer fixation times when task difficulty is increased, whilst others report shorter fixation times. In the present study it is argued that, within a theoretical framework based upon a combined cognitive stage model of information processing, most of these differences can be reconciled. The difference is thought to lie in the type of task that is being performed, and (more specifically) in the approximate mental state for performing that task. Thus, fixation duration and scanning behaviour may be indicative of the mental state of the subject. These hypotheses were tested in two field experiments with 20 city bus drivers in the city of Berlin, and 12 car drivers in Maastricht, The Netherlands. Both groups contained experienced and inexperienced drivers. F o r data analysis and interpretation purposes, the field of view was divided into seven areas of interest. The courses were divded into segments (77 for the Berlin experiments, and 124 for the Maastricht), grouped according to situational similarity (e g, right turns, left turns, straight lanes) representing different degrees of difficulty, and selected for further analysis. The relative importance of an area of interest varied with the situational demands, as indicated by the dwell times per area of interest, thus con-
Controlling a complex system requires the management of an enormous amount of information. This information is very often temporal in nature. Prediction, action, plan choice and co-ordinating the actions of several people all involve reasoning about time. Three temporal structures are confronted in man-machine interactions: machine, man and team. These temporal interactions need to be grasped in any analysis. In particular, they seem essential in a Human Reliability Analysis, as well as in an intelligent display design approach. An analysis of man-machine interactions in a complex dynamic environment, and particularly during a plant start-up situation, constitutes the basis of the concepts developed. The case study presented here shows how process plant operators face the time complexity o f a plant start-up. This peculiar situation offers a very vivid o p p o r t u n i t y to analyse the mechanisms o f temporal reasoning. In particular, mechanisms of time internatisation and temporal pattern matching have been found to be very helpful for temporal strategies. Some difficulties encountered by the operator in the estimation of temporal sequences, time duration and time of action have been analysed with regard to possible temporal errors.
performance of hypothetical cueing systems. These ranged from a 'perfect' system (i e, 100% hits, no misses and no false alarms), to a ' p o o r ' system (which cues 60% of the targets, misses the other 40%, and registers 33% false alarms). The remaining two systems were 'low risk' and 'high risk. The high-risk system cued all the targets, but also cued 33% false alarms. The observers were not informed about the criterion used in cued scenes. They were told only that the cueing system might cue some non-targets, and might miss some targets. The imagery was dynamic air-to-ground thermal scenes of farmland and villages. The targets were military vehicles. The cues were 'V' shapes placed above the object. Cueing began as soon as the object was visible, and followed the object continuously as it passed from the screen. The results show that the presence of cues can be beneficial to human search performance by reducing false designations, but there is no advantage in cueing all targets. There is an advantage in cueing only real targets (keeping cues to a minimum). Although all cueing systems obtained a higher or equal rate o f target designation from observers than uncued search, the difference was n o t significant. The greatest increase in designation rate was 14%. [t was found that significantly fewer false alarms were designated with three of the four cueing systems, compared with uncued search. The high-risk system produced as m a n y false alarm designations as uncued search. Also, different cueing systems resulted in significantly different designation strategies by the human observer: uncued targets were designated more than cued targets in some cases, while uncued targets were rarely designated in other cases. The results indicate that observer expectations about the reliability of the cueing system might be affected by the number of cues presented. Where a large number of cues is presented, more errors are expected, so more cued items are rejected and more uncued items are designated.
22.3.8 (119601) Car L K.T. An investigation into the effects o f a simulated thermal cueing aid upon air-to-ground search performance. In: D. Brogan (Ed). Visual search, Taylor & Francis, London, 1990, pp 3 6 1 - 3 7 0 , 21 refs.
22.3.9 (119602) Carver, E.M. Search o f imagery from airborne sensors - implications for selection of sensor and method of changing field-ofview. In: D. Brogan (Ed). Visual search, Taylor & Francis, London, 1990, pp 3 7 1 - 3 8 2 , 11 refs.
An experiment was carried out to make a preliminary assessment of the benefits to human search performance which can be gained from automatic cueing of target-like signatures in thermal imagery. F o u r different cueing criteria were used in simulating the
Reconnaissance systems are becoming increasingly complex, providing more and more information, and capabilities to the image interpreter. The overriding question is: Can the observer cope with the imagery that is presented to him? This
firming that the method of data reduction is useful, and prevents loss o f significant information. F i x a t i o n duration decreases with increasing situation complexity. Furthermore, fixations of extreme short duration occur less, with more experienced subjects. These data suggest that there exists a link between the control of fixations o f extreme short duration and the energetic state of the subject. 22.3.7 (119595)
Decortis, F., and De Keyser, V. Time: the Cinderella o f man-machine interaction. In: J. Ranta (Ed). Analysis, design and evaluation of man-machine systems 1988, Pergamon Press, Oxford, 1989, pp 6 5 - 7 0 , 14 refs.
Applied Ergonomics
June 1991
205