- Email: [email protected]
Instructional text: The transition from page to screen
lEEK Trans on Systems. Man and (),bernetics. 1987, SMC-17(3), 478487. A concept for a direct manipulation interface to monitor and control waterbased Rankine cycle heat engines is discussed and illustrated. The computerdriven interface utilises measured plant data to form a model of the process. The model is presented in the form of an icon based upon the Rankine cycle. The icon is formed in terms of the temperature and entropy properties of water from various points within the Rankine cycle. In addition, real-time mimics of plant systems, which contain, control and interact with the process, are presented within the same display format. The image displayed (on a cathode-ray tube) is designated a systemprocess iconic display of plant operations. An inference engine driven by plant data updates the display of plant segments which compose the iconic display. The iconic display serves as a visual knowledge base of plant operation as the interface is based on a modelworld metaphor. A keyboard containing dedicated control keys serves as an interface to actuate control tasks allocated to human operators. A direct manipulation of the heat engine is achieved through the dedicated keys as the icon responds to plant reactions activated by the control tasks. The human operator evaluates the data presented in the system-process iconic display to determine if the goals of operation are being met. The workload imposed upon human operators to assess goals is minimised, making the human operator an effective supervisor of resources and also an active integrated member of plant operations. Moreover, as the process model is based on first principles, the human operator's cognitive tasks, such as diagnosis of an event, are simplified. The illustrations are based upon light water reactor nuclear power plants. However, as water is the basic coolant in-the large majority of fossil power plants, the concepts illustrated and discussed are also applicable to these facilities. The viewpoints and opinions expressed herein are the author's personal ones, and they are not to be interpreted as the Nuclear Regulatory Commission's criteria, requirements or guidelines.
Display and control design 19.4.28 (108471)
Fieling, E., Pfitzmann, J., and Derisavi-F ard, F. Optimising input devices of computer aided design systems. In: Psychological issues of human-computer interaction in the workplace, M. Frese, E.Ulich and
342
Applied Ergonomics
W. Dzida (EdsL North-Holland, Amsterdam, 1987. pp 221--235.
Two types of vocabulary were compared in a simulated parcel sorting task using automatic speech recognition. ]'his article shows how menu tablet One type used place names drawn from devices (MTD) can be improved operational use, (e g, 'Belfast Delivery'): considerably by modifying the arrangein the other, alpha numeric codes based ment of functions. As manufacturers of on the International Civil Aviation CAD systems generally do not attach Organisation (ICAO) alphabet were great importance to the design of menu substituted for place names, (e g, 'Bravo tablet devices, the communication One'). A Kurzwell speech recogniser between user and system often causes was used in isolated mode. The overall problems. The aims of our projects rate of work was lower with codes were to develop an MTD that should be based on the ICAO alphabet than with structured systematically and designed in such a way as to meet the requirements place names. However, code recognition rates were similar for both of psychological graphic design. Thus, vocabularies; the ICAO alphabet gave both the training phase and the suban average rate of 78%, as compared sequent use of the system should be with 82% for place names. The ICAO simplified. The results of the study alphabet was superior in one respect; show the importance of an improved the proportion of failures which were MTD-design. An appropriate selection detectable - i e, instances where and grouping of functions as well as a recogniser output did not correspond standardisation of symbols improve the to any member of the code set - was user's communication with the system. substantially higher (98%1) than for the It also helps to remember the functions place names (88%). These results are and their appropriate symbols. discussed in terms of vocabulary design in general, and with specific reference to the development of a practical system 19.4.29 (108473) for parcel sorting. Wells, M.J., and Griffin, M.J. A review and investigation of aiming and tracking performance with head19.4.31 (108515) mounted sights. IEEE Trans on Systems, Spradlin, R.E. Man, and Cybernetics, 1987, SMC-17(2), Modern air transport flight deck design. 210-221. Displays Tech and Appl, 1987, 8(4), 171-182. The ability to control head movements determines the performance of The philosophy behind the flight head-mounted sights. A literature deck design of Boeing's 757/767 is review and the results of a number of outlined: by simplifying subsystem laboratory experiments investigating design, one can simplify control panel head aiming and tracking performance configurations which leads to simplified are presented. The literature review (the displays. This in turn results in results of which are included as a table) simplified crew procedures which is revealed that tracking performance consistent with a two-crew flight deck. may be degraded by in-flight conditions. The development of the fight deck is The experiments measured the frequency described, and the details of the display response of the head tracking system systems arrived at are shown. and systematically investigated, under laboratory conditions, the effects on performance of some of the variables 19.4.32 (108524) which may be present in an operational Kerr, S.T. environment. These included off-boreInstructional text: The transition from sight target angle, helmet weight, page to screen. Visible Language, 1986, seating conditions, the amplitude and 20(4), 3 6 8 - 3 9 2 . axis of target motion and reticle size Textual materials increasingly are and shape. It was shown that these being presented in electronic form. ,This variables had a relatively minor effect change creates problems for both on performance. It is recommended that creators and users of these materials. the influence of other relevant in-flight These problems arise because the variables, such as the restriction due physical form of electronic materials is to clothing and personal equipment quite different from that of printed and the effects of whole-body materials. The problems lie primarily vibration, should be investigated. in two areas: design of the surface, and design of the interface. Surface design 19.4.30 (108483) involved typography, layout, graphics Frankish, C.R., Jones, D.M., Madden, C., and illustrations, and the quality of Waight, K., and Stoddart, J. language; also important to consider Parcel sorting by speech recognition: are users' subjective reactions to these Human factors issues. In: People and elements. Interface design is closely computers III, D. Diaper and R. Winder tied to the 'wayfinding problem' (Eds). Cambridge University Press, helping users navigate through the text. Cambridge, 1987, pp 2 9 5 - 3 0 3 . The way finding problem manifests itself
December 1988
Where Are Those Back lnjunes Corrung From? Have you ever asked yourself this question? As ergonomists, we ask this question every day. In our search for accurate and meaningful answers, we have tried all of the existing ergonomic software an¢ analysis techniques. None of the were able to provide us with the precise and timely answers we needed. We responded to the emile Our engineering team set out to develop an easy to use software package which identifies workpl tasks likely to cause back injury We wanted a program that not require any expensive digitb equipment, a program that wou take advantage of one of our most refined tools: our eyes. We wanted a program that would analyze an entire job from beginning to end. It had to be sophisticated enough to take into account human motion, because no work is performed without movement. The result is BaekSoft, the first truly versatile and complete back injury assessment tool. Using BackSoft you will be able to easily identify workplace tasks which contribute to back injury. BackSoft begins with a series of questions
concerning employee characteristics. Workplace postures are then selected from a gallery of visual icons. The time duration for each task is entered into the program to allow for the ' -'culation of the effects of body wement on spinal force. ilizing this information,BackSoft culates dynamic workplace 2SS.
Quantitative graphs display -k, elbow, shoulder and knee ces for all tasks analyzed. OSH recommended cutoff limits prominently indicated to alert tl to tasks which may produce .'k injuries. In addition, a time ighted average for spinal force is calculated to allow for realistic task stress comparisons. BaekSofl runs on any IBM*PC or compatible computer and is menu driven for fast and easy operation. This new and unique ergonomic program is not copy protected and comes complete with an easy to use manual and pre-printed data collection pad. Now, you can find out where those back injuries are coming from. BCA. Excellence in Ergonomics. TM *Registered Trade Mark of International
Talk #: 1 Task dmrlpkn: OynamicJob Slmuladon
J~: LRIh~ Jlel
L5/$1 COMPRIES~ REACTIVEFORCE DURIN6A HF.AVYUFT 12.0SEC)
Business Machines Corporation.
KNEETORQUEDURINGA UFT ~
7200
PALLETTO OVERHEAD
~t10, -'---0511
56~5 AVli=46~
©
1188
3315
50
2100 ,O7 WOULDYOU UKE TO SIMULATEANOTHERTASK?if/Ill
1Ira+
4650
i8 TIME (SEC)
--__561 _ . . . . . .
- ......
----
-56 I+11 lso 2.22 2.77 3,83 388 4.44 4~
Lead = 45 Kos
TIME ISECI
Load = 25,7"I
BackSoft: Workplace Assessment Software is unconditionally guaranteed. Introductory Price: U.S. $495.00 Price includes air shipping and handling. Prepayment requested for overseas orders. PROD UCT CODE." BS W426
hf_a
BIOMECHANICS CORPORATION OF AMERICA Executive office: 337 Skidmore Road, Deer Park, NY 11729 1-800-248-ERGO in NY 516-243-3034 TELEX 221213 ATTN: BCA
Applied Ergonomics
December 1988
343
on three different levels: the immediate structure of the text (how information is provided at the page level), the internal structure (how such information is provided within a given document), and the external structure (navigational aids that allow users to move from one document to another). Three directions for further research are identified: realistic studies of use and search through electronic text; studies of how users represent to themselves the structure of text; and how users might best be introduced to environments incorporating electronic text.
Environment 19.4.33 (108556)
Rasyid, R., and Siswanto, A. The effects of illumination on productivity. In: Ergonomics in developing countries: An international symposium. International Labour Office, Geneva, 1987, pp 3 2 0 - 3 2 4 . The effects of illumination on productivity were studied on 30 female workers engaged in roiling operations in a cigarette manufacturing company. All variables such as age, duration of work, marital status, education, health and nutritional status, as well as the worker's skill, were taken into consideration in selecting the subjects. The subjects were exposed to different levels of illumination, starting from 100 lux up to 500 lux at intervals of 100 lux, and hourly performance indicators at each level of illumination were measured. The result of this study showed that increasing the light intensity from 100 lux to 500 lux resulted in the increase of 9"5% in hourly output.
19.4.34 (108574)
heart rate during an average work/rest cycle, of 110 beats/min. Subjects were six acclimatised, fit males. Skin temperature, rectal temperature and heart rate were monitored. They performed block-stepping at a metabolic rate of 450 W at 27, 28, 29, 30 and 31°C wet-bulb globe temperature. Humidity was low. Exposures were for 5 h on each day, on a 45/15 min work/rest schedule. Heart rates were measured and heartrate indices calculated. Correlation between the indices and the resting heart rate were determined. The highest correlation (r = 0"747, p < 0'001 ) was found between resting rate and the '5th hour cycle rate' (the average work/rest cycle heart rate during the fifth hour). Results indicate that the resting heart rate (measured on a seated individual after 10 min exposure to the conditions under investigation), has predictive value for calculating 'cycle rate'.
Work design and organisation
Gagnon, M., Akre, F., Chehade, A., Kemp, F., and Lortie, M.
Design principles for human-computer interfaces. In: Applications of cognitive psychology: Problem solving, education and computing. D.E. Berger, K. Pezdek and W.P. Banks (Eds). Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1987, pp 1 4 1 - 1 6 2 .
Mechanical work and energy transfers while turning patients in bed. Ergonomics, 1987, 30(11) 1515-1530.
If the field of human factors in computer systems is to be a success it must develop design principles that are useful; principles that apply across a wide range of technologies. In the first part of this paper, the author discusses some of the properties that useful principles should have. The second part of the paper is intended to illustrate the first part through the example of trade-off analysis.
Investigation into the performance of strenuous work at high environmental temperatures - the relationship between heart rate and a fixed work/ rest ratio. Int J Indust Ergonomics, 1988, 2(2), 131-141.
Women, men, VDU work and health: A questionnaire survey of British VDU operators. Work and Stress, 1987, 1(3), 271-283.
Employees in industry may be required to work in hot conditions which can result in heat strain. If work is to continue in potentially dangerous conditions, recommendations are needed to ensure that adequate precautions are taken. A requirement for the implementation o f these recommendations is a simple means of assessing the suitability of work/rest periods. This paper describes the first part of a study to develop simple predictive methods, related to the World Health Organisation limit of a
This paper presents the results of a questionnaire survey of male and female VDU operators distributed through Health & Safety at Work magazine. 3819 questionnaires were analysed using the SPSS computer programme. 57% of the sample were female, 68% were under 35 years old and 73% were members of a trade union or staff association. The large number of male respondents meant that it was possible to compare work patterns, types of work and health effects for men and women. It appears that women are engaged in more
Applied Ergonomics
t9.4.37 (108693)
]9.4.35 (]08663) Norman, D.A.
Kok, R., Senior, J., Schiefer, R.E., Lewis, M.I., and Meese, G.B.
344
repetitive and less varied tasks at the VDU and that they work longer hours a n d f o r longer periods without a break than men. The most frequently reported health problems were eye. strain, painful or stiff neck and shoulders, fatigue and irritated eyes. The incidence of symptoms was related to hours of work at the VDU. Women were more likely to report health effects than men. This difference remains when hours of work, type of work and hours worked without a break are taken into account. Ergonomically designed equipment such as adjustable chairs, lighting or keyboard did not have an obvious effect on the reporting of symptoms. It appeared that there is a complex interaction between the physical, ergonomic and psychosocial factors associated with new technology. All these factors need to be taken into account in further research into the health problems of VDU operators.
19.4.36 (108665)
Evans, J.
December 1988
The task of pulling and turning a patient in bed using a pique has been identified as potentially risky for female nursing aides and evaluated in terms of its loads on the spine. The present study investigated the mechanical work and energy transfers both between and within the body segments, and the relative contribution of the body segments to production of work. Fifteen female nursing aides took part in the experiment. Different task execution parameters were examined: execution velocity, height of the bed, direction of effort, leg position, support on the bedside. A 'free' task and a manual task not involving the use of the pique were also examined. Cinematography and force platforms were used to generate the data. Internal work was calculated on the basis of potential and kinetic segment energy. External work was calculated from the integration of power applied to the patient over time. The results suggest that forces should be applied vertically and at slow speed to minimise energy use: however, speed reduction leads to higher spinal loads and recommendations to this effect should be interpreted with care. The type of task examined was associated with little energy conservation (about 30%). Substantial use of the trunk segment to produce work might account for the back problems female nursing aides encounter with this type of task.
Display and control design 19.4.28 (108471)
Fieling, E., Pfitzmann, J., and Derisavi-F ard, F. Optimising input devices of computer aided design systems. In: Psychological issues of human-computer interaction in the workplace, M. Frese, E.Ulich and
342
Applied Ergonomics
W. Dzida (EdsL North-Holland, Amsterdam, 1987. pp 221--235.
Two types of vocabulary were compared in a simulated parcel sorting task using automatic speech recognition. ]'his article shows how menu tablet One type used place names drawn from devices (MTD) can be improved operational use, (e g, 'Belfast Delivery'): considerably by modifying the arrangein the other, alpha numeric codes based ment of functions. As manufacturers of on the International Civil Aviation CAD systems generally do not attach Organisation (ICAO) alphabet were great importance to the design of menu substituted for place names, (e g, 'Bravo tablet devices, the communication One'). A Kurzwell speech recogniser between user and system often causes was used in isolated mode. The overall problems. The aims of our projects rate of work was lower with codes were to develop an MTD that should be based on the ICAO alphabet than with structured systematically and designed in such a way as to meet the requirements place names. However, code recognition rates were similar for both of psychological graphic design. Thus, vocabularies; the ICAO alphabet gave both the training phase and the suban average rate of 78%, as compared sequent use of the system should be with 82% for place names. The ICAO simplified. The results of the study alphabet was superior in one respect; show the importance of an improved the proportion of failures which were MTD-design. An appropriate selection detectable - i e, instances where and grouping of functions as well as a recogniser output did not correspond standardisation of symbols improve the to any member of the code set - was user's communication with the system. substantially higher (98%1) than for the It also helps to remember the functions place names (88%). These results are and their appropriate symbols. discussed in terms of vocabulary design in general, and with specific reference to the development of a practical system 19.4.29 (108473) for parcel sorting. Wells, M.J., and Griffin, M.J. A review and investigation of aiming and tracking performance with head19.4.31 (108515) mounted sights. IEEE Trans on Systems, Spradlin, R.E. Man, and Cybernetics, 1987, SMC-17(2), Modern air transport flight deck design. 210-221. Displays Tech and Appl, 1987, 8(4), 171-182. The ability to control head movements determines the performance of The philosophy behind the flight head-mounted sights. A literature deck design of Boeing's 757/767 is review and the results of a number of outlined: by simplifying subsystem laboratory experiments investigating design, one can simplify control panel head aiming and tracking performance configurations which leads to simplified are presented. The literature review (the displays. This in turn results in results of which are included as a table) simplified crew procedures which is revealed that tracking performance consistent with a two-crew flight deck. may be degraded by in-flight conditions. The development of the fight deck is The experiments measured the frequency described, and the details of the display response of the head tracking system systems arrived at are shown. and systematically investigated, under laboratory conditions, the effects on performance of some of the variables 19.4.32 (108524) which may be present in an operational Kerr, S.T. environment. These included off-boreInstructional text: The transition from sight target angle, helmet weight, page to screen. Visible Language, 1986, seating conditions, the amplitude and 20(4), 3 6 8 - 3 9 2 . axis of target motion and reticle size Textual materials increasingly are and shape. It was shown that these being presented in electronic form. ,This variables had a relatively minor effect change creates problems for both on performance. It is recommended that creators and users of these materials. the influence of other relevant in-flight These problems arise because the variables, such as the restriction due physical form of electronic materials is to clothing and personal equipment quite different from that of printed and the effects of whole-body materials. The problems lie primarily vibration, should be investigated. in two areas: design of the surface, and design of the interface. Surface design 19.4.30 (108483) involved typography, layout, graphics Frankish, C.R., Jones, D.M., Madden, C., and illustrations, and the quality of Waight, K., and Stoddart, J. language; also important to consider Parcel sorting by speech recognition: are users' subjective reactions to these Human factors issues. In: People and elements. Interface design is closely computers III, D. Diaper and R. Winder tied to the 'wayfinding problem' (Eds). Cambridge University Press, helping users navigate through the text. Cambridge, 1987, pp 2 9 5 - 3 0 3 . The way finding problem manifests itself
December 1988
Where Are Those Back lnjunes Corrung From? Have you ever asked yourself this question? As ergonomists, we ask this question every day. In our search for accurate and meaningful answers, we have tried all of the existing ergonomic software an¢ analysis techniques. None of the were able to provide us with the precise and timely answers we needed. We responded to the emile Our engineering team set out to develop an easy to use software package which identifies workpl tasks likely to cause back injury We wanted a program that not require any expensive digitb equipment, a program that wou take advantage of one of our most refined tools: our eyes. We wanted a program that would analyze an entire job from beginning to end. It had to be sophisticated enough to take into account human motion, because no work is performed without movement. The result is BaekSoft, the first truly versatile and complete back injury assessment tool. Using BackSoft you will be able to easily identify workplace tasks which contribute to back injury. BackSoft begins with a series of questions
concerning employee characteristics. Workplace postures are then selected from a gallery of visual icons. The time duration for each task is entered into the program to allow for the ' -'culation of the effects of body wement on spinal force. ilizing this information,BackSoft culates dynamic workplace 2SS.
Quantitative graphs display -k, elbow, shoulder and knee ces for all tasks analyzed. OSH recommended cutoff limits prominently indicated to alert tl to tasks which may produce .'k injuries. In addition, a time ighted average for spinal force is calculated to allow for realistic task stress comparisons. BaekSofl runs on any IBM*PC or compatible computer and is menu driven for fast and easy operation. This new and unique ergonomic program is not copy protected and comes complete with an easy to use manual and pre-printed data collection pad. Now, you can find out where those back injuries are coming from. BCA. Excellence in Ergonomics. TM *Registered Trade Mark of International
Talk #: 1 Task dmrlpkn: OynamicJob Slmuladon
J~: LRIh~ Jlel
L5/$1 COMPRIES~ REACTIVEFORCE DURIN6A HF.AVYUFT 12.0SEC)
Business Machines Corporation.
KNEETORQUEDURINGA UFT ~
7200
PALLETTO OVERHEAD
~t10, -'---0511
56~5 AVli=46~
©
1188
3315
50
2100 ,O7 WOULDYOU UKE TO SIMULATEANOTHERTASK?if/Ill
1Ira+
4650
i8 TIME (SEC)
--__561 _ . . . . . .
- ......
----
-56 I+11 lso 2.22 2.77 3,83 388 4.44 4~
Lead = 45 Kos
TIME ISECI
Load = 25,7"I
BackSoft: Workplace Assessment Software is unconditionally guaranteed. Introductory Price: U.S. $495.00 Price includes air shipping and handling. Prepayment requested for overseas orders. PROD UCT CODE." BS W426
hf_a
BIOMECHANICS CORPORATION OF AMERICA Executive office: 337 Skidmore Road, Deer Park, NY 11729 1-800-248-ERGO in NY 516-243-3034 TELEX 221213 ATTN: BCA
Applied Ergonomics
December 1988
343
on three different levels: the immediate structure of the text (how information is provided at the page level), the internal structure (how such information is provided within a given document), and the external structure (navigational aids that allow users to move from one document to another). Three directions for further research are identified: realistic studies of use and search through electronic text; studies of how users represent to themselves the structure of text; and how users might best be introduced to environments incorporating electronic text.
Environment 19.4.33 (108556)
Rasyid, R., and Siswanto, A. The effects of illumination on productivity. In: Ergonomics in developing countries: An international symposium. International Labour Office, Geneva, 1987, pp 3 2 0 - 3 2 4 . The effects of illumination on productivity were studied on 30 female workers engaged in roiling operations in a cigarette manufacturing company. All variables such as age, duration of work, marital status, education, health and nutritional status, as well as the worker's skill, were taken into consideration in selecting the subjects. The subjects were exposed to different levels of illumination, starting from 100 lux up to 500 lux at intervals of 100 lux, and hourly performance indicators at each level of illumination were measured. The result of this study showed that increasing the light intensity from 100 lux to 500 lux resulted in the increase of 9"5% in hourly output.
19.4.34 (108574)
heart rate during an average work/rest cycle, of 110 beats/min. Subjects were six acclimatised, fit males. Skin temperature, rectal temperature and heart rate were monitored. They performed block-stepping at a metabolic rate of 450 W at 27, 28, 29, 30 and 31°C wet-bulb globe temperature. Humidity was low. Exposures were for 5 h on each day, on a 45/15 min work/rest schedule. Heart rates were measured and heartrate indices calculated. Correlation between the indices and the resting heart rate were determined. The highest correlation (r = 0"747, p < 0'001 ) was found between resting rate and the '5th hour cycle rate' (the average work/rest cycle heart rate during the fifth hour). Results indicate that the resting heart rate (measured on a seated individual after 10 min exposure to the conditions under investigation), has predictive value for calculating 'cycle rate'.
Work design and organisation
Gagnon, M., Akre, F., Chehade, A., Kemp, F., and Lortie, M.
Design principles for human-computer interfaces. In: Applications of cognitive psychology: Problem solving, education and computing. D.E. Berger, K. Pezdek and W.P. Banks (Eds). Lawrence Erlbaum Associates, Hillsdale, New Jersey, 1987, pp 1 4 1 - 1 6 2 .
Mechanical work and energy transfers while turning patients in bed. Ergonomics, 1987, 30(11) 1515-1530.
If the field of human factors in computer systems is to be a success it must develop design principles that are useful; principles that apply across a wide range of technologies. In the first part of this paper, the author discusses some of the properties that useful principles should have. The second part of the paper is intended to illustrate the first part through the example of trade-off analysis.
Investigation into the performance of strenuous work at high environmental temperatures - the relationship between heart rate and a fixed work/ rest ratio. Int J Indust Ergonomics, 1988, 2(2), 131-141.
Women, men, VDU work and health: A questionnaire survey of British VDU operators. Work and Stress, 1987, 1(3), 271-283.
Employees in industry may be required to work in hot conditions which can result in heat strain. If work is to continue in potentially dangerous conditions, recommendations are needed to ensure that adequate precautions are taken. A requirement for the implementation o f these recommendations is a simple means of assessing the suitability of work/rest periods. This paper describes the first part of a study to develop simple predictive methods, related to the World Health Organisation limit of a
This paper presents the results of a questionnaire survey of male and female VDU operators distributed through Health & Safety at Work magazine. 3819 questionnaires were analysed using the SPSS computer programme. 57% of the sample were female, 68% were under 35 years old and 73% were members of a trade union or staff association. The large number of male respondents meant that it was possible to compare work patterns, types of work and health effects for men and women. It appears that women are engaged in more
Applied Ergonomics
t9.4.37 (108693)
]9.4.35 (]08663) Norman, D.A.
Kok, R., Senior, J., Schiefer, R.E., Lewis, M.I., and Meese, G.B.
344
repetitive and less varied tasks at the VDU and that they work longer hours a n d f o r longer periods without a break than men. The most frequently reported health problems were eye. strain, painful or stiff neck and shoulders, fatigue and irritated eyes. The incidence of symptoms was related to hours of work at the VDU. Women were more likely to report health effects than men. This difference remains when hours of work, type of work and hours worked without a break are taken into account. Ergonomically designed equipment such as adjustable chairs, lighting or keyboard did not have an obvious effect on the reporting of symptoms. It appeared that there is a complex interaction between the physical, ergonomic and psychosocial factors associated with new technology. All these factors need to be taken into account in further research into the health problems of VDU operators.
19.4.36 (108665)
Evans, J.
December 1988
The task of pulling and turning a patient in bed using a pique has been identified as potentially risky for female nursing aides and evaluated in terms of its loads on the spine. The present study investigated the mechanical work and energy transfers both between and within the body segments, and the relative contribution of the body segments to production of work. Fifteen female nursing aides took part in the experiment. Different task execution parameters were examined: execution velocity, height of the bed, direction of effort, leg position, support on the bedside. A 'free' task and a manual task not involving the use of the pique were also examined. Cinematography and force platforms were used to generate the data. Internal work was calculated on the basis of potential and kinetic segment energy. External work was calculated from the integration of power applied to the patient over time. The results suggest that forces should be applied vertically and at slow speed to minimise energy use: however, speed reduction leads to higher spinal loads and recommendations to this effect should be interpreted with care. The type of task examined was associated with little energy conservation (about 30%). Substantial use of the trunk segment to produce work might account for the back problems female nursing aides encounter with this type of task.