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Human factors for portable products
appropriate chair specifications can be more readily defined. A description is given of approaches to these problems, and the solution adopted, from an anthropometric survey carried out on elderly and disabled people by the Institute for Consumer Ergonomics.
14.1.18 (82738)
maximum portable weight was found to be 7.3 kg. In addition wrist rotation strengths in the vertical upright position used for one-handed carry were recorded for the 5 - 9 5 percentile male and female to aid in the determination of correct handle placement and case balance. 14.1.20 (83001)
Ridd, J.E., and Davis, P.R.
Malmqvist, R. et al
Industrial human factors research in a British Health and Safety Institute. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October 1981, Edited by Robert C. Sugarman, 1981, pp 5 4 1 - 5 4 5 .
Measurement of localised muscle fatigue in building work. Ergonomics, 1981, 24.9, 6 9 5 - 7 0 9 .
The role of the Materials Handling Research Unit (MHRU) within the Health and Safety Institute is to investigate industrial manual handling problems and their associated accidents, In particular the Unit's work is directed towards the prevention of back disorders which constitute the largest single attributed cause of absence for manual handling accidents. This research is directed firstly at ameliorating existing handling problems in industry and, secondly, establishing safe guidelines for the design of future working environments. To this end the Unit has developed an analytical method which when applied to a particular industry can identify those areas where the risk of accidents and injury is greatest, and hence where preventative measures may have most effect. Of the industrial groups studied to date by the MHRU several are included here to illustrate the complete methodology. 14.1.19 (82740)
Rosenberg, D.J. Human factors for portable products. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October, 1981, Edited by Robert C. Sugarman, 1981, pp 3 1 7 - 3 2 1 . The parameter of weight was investigated to determine the correct poundage of a portable product for the 5 - 9 5 percentile male and female consumer. The concept of portability appears to be culturally inspired such that men and women do not differ in the amount of weight which they feel is portable. Men, however, tend to use approximately 30% of their maximum isometric arm strength when carrying what they feel to be a portable object, while women utilise slightly over 40% of their maximum isometric arm strength to carry the same weight. For the subject group as a whole the correct maximum portable weight ranges from 4"5 kg at the fifth percentile to 10-2 kg at the 95th percentile. The 50th percentile
quality and environmental requirements which have to be met by electronic displays for use in aircraft. The present paper explores in more detail the visual aspects of electrooptical displays in the light of what is known about the performance capability of the optical system of the operators who will use the displays.
14.1.22 (82762)
Woods, D.D., Wise, J.A., and Hanes, L.F.
The loads on the shoulder muscles of building workers were investigated by applying a new fatigue index method, for evaluation of localised muscle fatigue during work. Based on a power spectrum analysis of myoelectric signals, and calculations of spectral moments, the method enables the monitoring of changes in the propagation velocity of muscle fibre action potentials. The propagation velocity alters with the integrated response to the strain of the load on muscle metabolism and circulation. Myoelectric signals from four shoulder muscles as well as the ECG were recorded on magnetic tape at the building sites during regular daily work. For analysis, specially developed computerised procedures were used, including procedures for automatic checks of signal quality. Significant localised muscle fatigue was found in one or more muscles during a spell of work. The fatigue was particularly marked in the supraspinatus and trapezius muscles, and was seen in static work tasks even when the force exerted was small. This indicates that a stereotyped task has a greater tendency to give localised muscle fatigue than a more varied one, even if the latter is heavier. The present investigation also shows that methods measuring oxygen consumption or pulse rate are not sufficiently sensitive for monitoring the influence of localised loads. Quantitative electromyography, on the other hand, permits load measurements on single muscles.
An evaluation of nuclear power plant safety parameter display systems. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October 1981, Edited by Robert C. Sugarman, 1981, pp 1 1 0 114. Two proposed safety parameter display systems, of the type to be required in nuclear power plant control rooms, were evaluated using a training simulator and experienced crews undergoing refresher training. A decision analysis approach was used. The discussion addresses the effectiveness of the training situation as an evaluation tool and methodological issues. 14.1.23 (82774)
Szlichcinski, K.P. The design of symbols and pictograms. British Telecom Research Laboratories, Martlesham Heath, Ipswich, Research Department Report No 875, 1980, 12 pp. The differences between symbols and pictograms are discussed, and guidelines on their design and use are presented. Many design decisions can be resolved by a careful consideration of the purpose and readership of the symbol or pictogram, and of the environment in which it will be displayed. Particular emphasis is placed on testing the comprehensibility of symbols and the effectiveness with which pictograms communicate information before they are given wide circulation. 14.1.24 (82780)
Hartley, J., and Trueman, M.
Visual displays
The effects of changes in layout and changes in wording on preferences for instructional text. Visible Language, 1981, 15.1, 13-31.
14.1.21 (82760) Laycock, J., and Chorley, R.A. Human factors considerations for the interface between an electro-optical display and the human visual system.
Displays Technology and Applications, 1981, 2.6, 3 0 4 - 3 1 4 . A paper by one of the present authors has been published (Displays Technology and Applications, 1.3, 1 5 9 - 1 6 1 ) which reviews the historical background to modern aircraft display systems, and indicates some of the
Judges rated their preferences for pages of instructional text which varied in terms of their layout, their wording or both of these features. Three different methods of assessing preferences were used. The results suggested that these measures could provide useful rough quantitative data but that they could not be relied upon too greatly when fine judgement was required.
Applied Ergonomics
March 1983
73
14.1.18 (82738)
maximum portable weight was found to be 7.3 kg. In addition wrist rotation strengths in the vertical upright position used for one-handed carry were recorded for the 5 - 9 5 percentile male and female to aid in the determination of correct handle placement and case balance. 14.1.20 (83001)
Ridd, J.E., and Davis, P.R.
Malmqvist, R. et al
Industrial human factors research in a British Health and Safety Institute. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October 1981, Edited by Robert C. Sugarman, 1981, pp 5 4 1 - 5 4 5 .
Measurement of localised muscle fatigue in building work. Ergonomics, 1981, 24.9, 6 9 5 - 7 0 9 .
The role of the Materials Handling Research Unit (MHRU) within the Health and Safety Institute is to investigate industrial manual handling problems and their associated accidents, In particular the Unit's work is directed towards the prevention of back disorders which constitute the largest single attributed cause of absence for manual handling accidents. This research is directed firstly at ameliorating existing handling problems in industry and, secondly, establishing safe guidelines for the design of future working environments. To this end the Unit has developed an analytical method which when applied to a particular industry can identify those areas where the risk of accidents and injury is greatest, and hence where preventative measures may have most effect. Of the industrial groups studied to date by the MHRU several are included here to illustrate the complete methodology. 14.1.19 (82740)
Rosenberg, D.J. Human factors for portable products. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October, 1981, Edited by Robert C. Sugarman, 1981, pp 3 1 7 - 3 2 1 . The parameter of weight was investigated to determine the correct poundage of a portable product for the 5 - 9 5 percentile male and female consumer. The concept of portability appears to be culturally inspired such that men and women do not differ in the amount of weight which they feel is portable. Men, however, tend to use approximately 30% of their maximum isometric arm strength when carrying what they feel to be a portable object, while women utilise slightly over 40% of their maximum isometric arm strength to carry the same weight. For the subject group as a whole the correct maximum portable weight ranges from 4"5 kg at the fifth percentile to 10-2 kg at the 95th percentile. The 50th percentile
quality and environmental requirements which have to be met by electronic displays for use in aircraft. The present paper explores in more detail the visual aspects of electrooptical displays in the light of what is known about the performance capability of the optical system of the operators who will use the displays.
14.1.22 (82762)
Woods, D.D., Wise, J.A., and Hanes, L.F.
The loads on the shoulder muscles of building workers were investigated by applying a new fatigue index method, for evaluation of localised muscle fatigue during work. Based on a power spectrum analysis of myoelectric signals, and calculations of spectral moments, the method enables the monitoring of changes in the propagation velocity of muscle fibre action potentials. The propagation velocity alters with the integrated response to the strain of the load on muscle metabolism and circulation. Myoelectric signals from four shoulder muscles as well as the ECG were recorded on magnetic tape at the building sites during regular daily work. For analysis, specially developed computerised procedures were used, including procedures for automatic checks of signal quality. Significant localised muscle fatigue was found in one or more muscles during a spell of work. The fatigue was particularly marked in the supraspinatus and trapezius muscles, and was seen in static work tasks even when the force exerted was small. This indicates that a stereotyped task has a greater tendency to give localised muscle fatigue than a more varied one, even if the latter is heavier. The present investigation also shows that methods measuring oxygen consumption or pulse rate are not sufficiently sensitive for monitoring the influence of localised loads. Quantitative electromyography, on the other hand, permits load measurements on single muscles.
An evaluation of nuclear power plant safety parameter display systems. In: Proceedings of the Human Factors Society 25th Annual Meeting, Rochester, New York, 1 2 - 1 6 October 1981, Edited by Robert C. Sugarman, 1981, pp 1 1 0 114. Two proposed safety parameter display systems, of the type to be required in nuclear power plant control rooms, were evaluated using a training simulator and experienced crews undergoing refresher training. A decision analysis approach was used. The discussion addresses the effectiveness of the training situation as an evaluation tool and methodological issues. 14.1.23 (82774)
Szlichcinski, K.P. The design of symbols and pictograms. British Telecom Research Laboratories, Martlesham Heath, Ipswich, Research Department Report No 875, 1980, 12 pp. The differences between symbols and pictograms are discussed, and guidelines on their design and use are presented. Many design decisions can be resolved by a careful consideration of the purpose and readership of the symbol or pictogram, and of the environment in which it will be displayed. Particular emphasis is placed on testing the comprehensibility of symbols and the effectiveness with which pictograms communicate information before they are given wide circulation. 14.1.24 (82780)
Hartley, J., and Trueman, M.
Visual displays
The effects of changes in layout and changes in wording on preferences for instructional text. Visible Language, 1981, 15.1, 13-31.
14.1.21 (82760) Laycock, J., and Chorley, R.A. Human factors considerations for the interface between an electro-optical display and the human visual system.
Displays Technology and Applications, 1981, 2.6, 3 0 4 - 3 1 4 . A paper by one of the present authors has been published (Displays Technology and Applications, 1.3, 1 5 9 - 1 6 1 ) which reviews the historical background to modern aircraft display systems, and indicates some of the
Judges rated their preferences for pages of instructional text which varied in terms of their layout, their wording or both of these features. Three different methods of assessing preferences were used. The results suggested that these measures could provide useful rough quantitative data but that they could not be relied upon too greatly when fine judgement was required.
Applied Ergonomics
March 1983
73