Friday, 25 March 2011 04:39

Psychosocial Aspects of VDU Work

Written by
Rate this item
(0 votes)


Computers provide efficiency, competitive advantages and the ability to carry out work processes that would not be possible without their use. Areas such as manufacturing process control, inventory management, records management, complex systems control and office automation have all benefited from automation. Computerization requires substantial infrastructure support in order to function properly. In addition to architectural and electrical changes needed to accommodate the machines themselves, the introduction of computerization requires changes in employee knowledge and skills, and application of new methods of managing work. The demands placed on jobs which use computers can be very different from those of traditional jobs. Often computerized jobs are more sedentary and may require more thinking and mental attention to tasks, while at the same time require less physical energy expenditure. Production demands can be high, with constant work pressure and little room for decision-making.

The economic advantages of computers at work have overshadowed associated potential health, safety and social problems for workers, such as job loss, cumulative trauma disorders and increased mental stress. The transition from more traditional forms of work to computerization has been difficult in many workplaces, and has resulted in significant psychosocial and sociotechnical problems for the workforce.

Psychosocial Problems Specific to VDUs

Research studies (for example, Bradley 1983 and 1989; Bikson 1987; Westlander 1989; Westlander and Aberg 1992; Johansson and Aronsson 1984; Stellman et al. 1987b; Smith et al. 1981 and 1992a) have documented how the introduction of computers into the workplace has brought substantial changes in the process of work, in social relationships, in management style and in the nature and content of job tasks. In the 1980s, the implementation of the technological changeover to computerization was most often a “top-down” process in which employees had no input into the decisions regarding the new technology or the new work structures. As a result, many industrial relations, physical and mental health problems arose.

Experts disagree on the success of changes that are occurring in offices, with some arguing that computer technology improves the quality of work and enhances productivity (Strassmann 1985), while others compare computers to earlier forms of technology, such as assembly-line production that also make working conditions worse and increase job stress (Moshowitz 1986; Zuboff 1988). We believe that visual display unit (VDU) technology does affect work in various ways, but technology is only one element of a larger work system that includes the individual, tasks, environment and organizational factors.

Conceptualizing Computerized Job Design

Many working conditions jointly influence the VDU user. The authors have proposed a comprehensive job design model which illustrates the various facets of working conditions which can interact and accumulate to produce stress (Smith and Carayon-Sainfort 1989). Figure 1 illustrates this conceptual model for the various elements of a work system that can exert loads on workers and may result in stress. At the centre of this model is the individual with his/her unique physical characteristics, perceptions, personality and behaviour. The individual uses technologies to perform specific job tasks. The nature of the technologies, to a large extent, determines performance and the skills and knowledge needed by the worker to use the technology effectively. The requirements of the task also affect the required skill and knowledge levels needed. Both the tasks and technologies affect the job content and the mental and physical demands. The model also shows that the tasks and technologies are placed within the context of a work setting that comprises the physical and the social environment. The overall environment itself can affect comfort, psychological moods and attitudes. Finally, the organizational structure of work defines the nature and level of individual involvement, worker interactions, and levels of control. Supervision and standards of performance are all affected by the nature of the organization.

Figure 1. Model of working conditions and their impact on the individual


This model helps to explain relationships between job requirements, psychological and physical loads and resulting health strains. It represents a systems concept in which any one element can influence any other element, and in which all elements interact to determine the way in which work is accomplished and the effectiveness of the work in achieving individual and organizational needs and goals. The application of the model to the VDU workplace is described below.




Physical environmental factors have been implicated as job stressors in the office and elsewhere. General air quality and housekeeping contribute, for example, to sick building syndrome and other stress responses (Stellman et al. 1985; Hedge, Erickson and Rubin 1992.) Noise is a well-known environmental stressor which can cause increases in arousal, blood pressure, and negative psychological mood (Cohen and Weinstein 1981). Environmental conditions that produce sensory disruption and make it more difficult to carry out tasks increase the level of worker stress and emotional irritation are other examples (Smith et al. 1981; Sauter et al. 1983b).


With the introduction of computer technology, expectations regarding performance increase. Additional pressure on workers is created because they are expected to perform at a higher level all the time. Excessive workload and work pressure are significant stressors for computer users (Smith et al. 1981; Piotrkowski, Cohen and Coray 1992; Sainfort 1990). New types of work demands are appearing with the increasing use of computers. For instance, cognitive demands are likely to be sources of increased stress for VDU users (Frese 1987). These are all facets of job demands.

Electronic Monitoring of Employee Performance

The use of electronic methods to monitor employee work performance has increased substantially with the widespread use of personal computers which make such monitoring quick and easy. Monitoring provides information which can be used by employers to better manage technological and human resources. With electronic monitoring it is possible to pinpoint bottlenecks, production delays and below average (or below standard) performance of employees in real time. New electronic communication technologies have the capability of tracking the performance of individual elements of a communication system and of pinpointing individual worker inputs. Such work elements as data entry into computer terminals, telephone conversations, and electronic mail messages can all be examined through the use of electronic surveillance.

Electronic monitoring increases management control over the workforce, and may lead to organisational management approaches that are stressful. This raises important issues about the accuracy of the monitoring system and how well it represents worker contributions to the employer’s success, the invasion of worker privacy, worker versus technology control over job tasks, and the implications of management styles that use monitored information to direct worker behaviour on the job (Smith and Amick 1989; Amick and Smith 1992; Carayon 1993b). Monitoring can bring about increased production, but it may also produce job stress, absences from work, turnover in the workforce and sabotage. When electronic monitoring is combined with incentive systems for increased production, work-related stress can also be increased (OTA 1987; Smith et al. 1992a). In addition, such electronic performance monitoring raises issues of worker privacy (ILO 1991) and several countries have banned the use of individual performance monitoring.

A basic requirement of electronic monitoring is that work tasks be broken up into activities that can easily be quantified and measured, which usually results in a job design approach that reduces the content of the tasks by removing complexity and thinking, which are replaced by repetitive action. The underlying philosophy is similar to a basic principle of “Scientific Management” (Taylor 1911) that calls for work “simplification.”

In one company, for example, a telephone monitoring capability was included with a new telephone system for customer service operators. The monitoring system distributed incoming telephone calls from customers, timed the calls and allowed for supervisor eavesdropping on employee telephone conversations. This system was instituted under the guise of a work flow scheduling tool for determining the peak periods for telephone calls to determine when extra operators would be needed. Instead of using the monitoring system solely for that purpose, management also used the data to establish work performance standards, (seconds per transaction) and to bring disciplinary action against employees with “below average performance.” This electronic monitoring system introduced a pressure to perform above average because of fear of reprimand. Research has shown that such work pressure is not conducive to good performance but rather can bring about adverse health consequences (Cooper and Marshall 1976; Smith 1987). In fact, the monitoring system described was found to have increased employee stress and lowered the quality of production (Smith et al. 1992a).

Electronic monitoring can influence worker self-image and feelings of self-worth. In some cases, monitoring could enhance feelings of self-worth if the worker gets positive feedback. The fact that management has taken an interest in the worker as a valuable resource is another possible positive outcome. However, both effects may be perceived differently by workers, particularly if poor performance leads to punishment or reprimand. Fear of negative evaluation can produce anxiety and may damage self-esteem and self-image. Indeed electronic monitoring can create known adverse working conditions, such as paced work, lack of worker involvement, reduced task variety and task clarity, reduced peer social support, reduced supervisory support, fear of job loss, or routine work activities, and lack of control over tasks (Amick and Smith 1992; Carayon 1993).

Michael J. Smith

Positive aspects also exist since computers are able to do many of the simple, repetitive tasks that were previously done manually, which can reduce the repetitiveness of the job, increase the content of the job and make it more meaningful. This is not universally true, however, since many new computer jobs, such as data entry, are still repetitive and boring. Computers can also provide performance feedback that is not available with other technologies (Kalimo and Leppanen 1985), which can reduce ambiguity.

Some aspects of computerized work have been linked to decreased control, which has been identified as a major source of stress for clerical computer users. Uncertainty regarding the duration of computer-related problems, such as breakdown and slowdown, can be a source of stress (Johansson and Aronsson 1984; Carayon-Sainfort 1992). Computer-related problems can be particularly stressful if workers, such as airline reservation clerks, are highly dependent on the technology to perform their job.


The technology being used by the worker often defines his or her ability to accomplish tasks and the extent of physiological and psychological load. If the technology produces either too much or too little workload, increased stress and adverse physical health outcomes can occur (Smith et al. 1981; Johansson and Aronsson 1984; Ostberg and Nilsson 1985). Technology is changing at a rapid pace, forcing workers to adjust their skills and knowledge continuously to keep up. In addition, today’s skills can quickly become obsolete. Technological obsolescence may be due to job de-skilling and impoverished job content or to inadequate skills and training. Workers who do not have the time or resources to keep up with the technology may feel threatened by the technology and may worry about losing their job. Thus, workers’ fears of having inadequate skills to use the new technology are one of the main adverse influences of technology, which training, of course, can help to offset. Another effect of the introduction of technology is the fear of job loss due to increased efficiency of technology (Ostberg and Nilsson 1985; Smith, Carayon and Miezio 1987).

Intensive, repetitive, long sessions at the VDU can also contribute to increased ergonomic stress and strain (Stammerjohn, Smith and Cohen 1981; Sauter et al. 1983b; Smith et al. 1992b) and can create visual or musculoskeletal discomfort and disorders, as described elsewhere in the chapter.

Organizational factors

The organizational context of work can influence worker stress and health. When technology requires new skills, the way in which workers are introduced to the new technology and the organizational support they receive, such as appropriate training and time to acclimatize, has been related to the levels of stress and emotional disturbances experienced (Smith, Carayon and Miezio 1987). The opportunity for growth and promotion in a job (career development) is also related to stress (Smith et al. 1981). Job future uncertainty is a major source of stress for computer users (Sauter et al. 1983b; Carayon 1993a) and the possibility of job loss also creates stress (Smith et al. 1981; Kasl 1978).

Work scheduling, such as shift work and overtime, have been shown to have negative mental and physical health consequences (Monk and Tepas 1985; Breslow and Buell 1960). Shift work is increasingly used by companies that want or need to keep computers running continuously. Overtime is often needed to ensure that workers keep up with the workload, especially when work remains incomplete as a result of delays due to computer breakdown or misfunction.

Computers provide management with the capability to continuously monitor employee performance electronically, which has the potential to create stressful working conditions, such as by increasing work pressure (see the box “Electronic Monitoring”). Negative employee-supervisor relationships and feelings of lack of control can increase in electronically supervised workplaces.

The introduction of VDU technology has affected social relationships at work. Social isolation has been identified as a major source of stress for computer users (Lindström 1991; Yang and Carayon 1993) since the increased time spent working on computers reduces the time that workers have to socialize and receive or give social support. The need for supportive supervisors and co-workers has been well documented (House 1981). Social support can moderate the impact of other stressors on worker stress. Thus, support from colleagues, supervisor or computer staff becomes important for the worker who is experiencing computer-related problems but the computer work environment may, ironically, reduce the level of such social support available.

The individual

A number of personal factors such as personality, physical health status, skills and abilities, physical conditioning, prior experiences and learning, motives, goals and needs determine the physical and psychological effects just described (Levi 1972).

Improving the Psychosocial Characteristics of VDU Work

The first step in making VDU work less stressful is to identify work organization and job design features that can promote psychosocial problems so that they can be modified, always bearing in mind that VDU problems which can lead to job stress are seldom the result of single aspects of the organization or of job design, but rather, are a combination of many aspects of improper work design. Thus, solutions for reducing or eliminating job stress must be comprehensive and deal with many improper work design factors simultaneously. Solutions that focus on only one or two factors will not succeed. (See figure 2.)

Figure 2. Keys to reducing isolation and stress


Improvements in job design should start with the work organization providing a supportive environment for employees. Such an environment enhances employee motivation to work and feelings of security, and it reduces feelings of stress (House 1981). A policy statement that defines the importance of employees within an organization and is explicit on how the organization will provide a supportive environment is a good first step. One very effective means for providing support to employees is to provide supervisors and managers with specific training in methods for being supportive. Supportive supervisors can serve as buffers that “protect” employees from unnecessary organizational or technological stresses.


The content of job tasks has long been recognized as important for employee motivation and productivity (Herzberg 1974; Hackman and Oldham 1976). More recently the relationship between job content and job stress reactions has been elucidated (Cooper and Marshall 1976; Smith 1987). Three main aspects of job content that are of specific relevance to VDU work are task complexity, employee skills and career opportunities. In some respects, these are all related to the concept of developing the motivational climate for employee job satisfaction and psychological growth, which deals with the improvement of employees’ intellectual capabilities and skills, increased ego enhancement or self-image and increased social group recognition of individual achievement.

The primary means for enhancing job content is to increase the skill level for performing job tasks, which typically means enlarging the scope of job tasks, as well as enriching the elements of each specific task (Herzberg 1974). Enlarging the number of tasks increases the repertoire of skills needed for successful task performance, and also increases the number of employee decisions made while defining task sequences and activities. An increase in the skill level of the job content promotes employee self-image of personal worth and of value to the organization. It also enhances the positive image of the individual in his or her social work group within the organization.

Increasing the complexity of the tasks, which means increasing the amount of thinking and decision-making involved, is a logical next step that can be achieved by combining simple tasks into sets of related activities that have to be coordinated, or by adding mental tasks that require additional knowledge and computational skills. Specifically, when computerized technology is introduced, new tasks in general will have requirements that exceed the current knowledge and skills of the employees who are to perform them. Thus there is a need to train employees in the new aspects of the tasks so that they will have the skills to perform the tasks adequately. Such training has more than one benefit, since it not only may improve employee knowledge and skills, and thus enhance performance, but may also enhance employee self-esteem and confidence. Providing training also shows the employee that the employer is willing to invest in his or her skill enhancement, and thus promotes confidence in employment stability and job future.

The amount of control that an employee has over the job has a powerful psychosocial influence (Karasek et al. 1981; Sauter, Cooper and Hurrell 1989). Important aspects of control can be defined by the answers to the questions, “What, how and when?” The nature of the tasks to be undertaken, the need for coordination among employees, the methods to be used to carry out the tasks and the scheduling of the tasks can all be defined by answers to these questions. Control can be designed into jobs at the levels of the task, the work unit and the organization (Sainfort 1991; Gardell 1971). At the task level, the employee can be given autonomy in the methods and procedures used in completing the task.

At the work-unit level, groups of employees can self-manage several interrelated tasks and the group itself can decide on who will perform particular tasks, the scheduling of tasks, coordination of tasks and production standards to meet organizational goals. At the organization level, employees can participate in structured activities that provide input to management about employee opinions or quality improvement suggestions. When the levels of control available are limited, it is better to introduce autonomy at the task level and then work up the organizational structure, insofar as possible (Gardell 1971).

One natural result of computer automation appears to be an increased workload, since the purpose of the automation is to enhance the quantity and quality of work output. Many organizations believe that such an increase is necessary in order to pay for the investment in the automation. However, establishing the appropriate workload is problematic. Scientific methods have been developed by industrial engineers for determining appropriate work methods and workloads (the performance requirements of jobs). Such methods have been used successfully in manufacturing industries for decades, but have had little application in office settings, even after office computerization. The use of scientific means, such as those described by Kanawaty (1979) and Salvendy (1992), to establish workloads for VDU operators, should be a high priority for every organization, since such methods set reasonable production standards or work output requirements, help to protect employees from excessive workloads, as well as help to ensure the quality of products.

The demand that is associated with the high levels of concentration required for computerized tasks can diminish the amount of social interaction during work, leading to social isolation of employees. To counter this effect, opportunities for socialization for employees not engaged in computerized tasks, and for employees who are on rest breaks, should be provided. Non-computerized tasks which do not require extensive concentration could be organized in such a way that employees can work in close proximity to one another and thus have the opportunity to talk among themselves. Such socialization provides social support, which is known to be an essential modifying factor in reducing adverse mental health effects and physical disorders such as cardiovascular diseases (House 1981). Socialization naturally also reduces social isolation and thus promotes improved mental health.

Since poor ergonomic conditions can also lead to psychosocial problems for VDU users, proper ergonomic conditions are an essential element of complete job design. This is covered in some detail in other articles in this chapter and elsewhere in the Encyclopaedia.

Finding Balance

Since there are no “perfect” jobs or “perfect” workplaces free from all psychosocial and ergonomic stressors, we must often compromise when making improvements at the workplace. Redesigning processes generally involves “trade-offs” between excellent working conditions and the need to have acceptable productivity. This requires us to think about how to achieve the best “balance” between positive benefits for employee health and productivity. Unfortunately, since so many factors can produce adverse psychosocial conditions that lead to stress, and since these factors are interrelated, modifications in one factor may not be beneficial if concomitant changes are not made in other related factors. In general, two aspects of balance should be addressed: the balance of the total system and compensatory balance.

System balance is based on the idea that a workplace or process or job is more than the sum of the individual components of the system. The interplay among the various components produces results that are greater (or less) than the sum of the individual parts and determines the potential for the system to produce positive results. Thus, job improvements must take account of and accommodate the entire work system. If an organization concentrates solely on the technological component of the system, there will be an imbalance because personal and psychosocial factors will have been neglected. The model given in figure 1 of the work system can be used to identify and understand the relationships between job demands, job design factors, and stress which must be balanced.

Since it is seldom possible to eliminate all psychosocial factors that cause stress, either because of financial considerations, or because it is impossible to change inherent aspects of job tasks, compensatory balance techniques are employed. Compensatory balance seeks to reduce psychological stress by changing aspects of work that can be altered in a positive direction to compensate for those aspects that cannot be changed. Five elements of the work system—physical loads, work cycles, job content, control, and socialization—function in concert to provide the resources for achieving individual and organizational goals through compensatory balance. While we have described some of the potential negative attributes of these elements in terms of job stress, each also has positive aspects that can counteract the negative influences. For instance, inadequate skill to use new technology can be offset by employee training. Low job content that creates repetition and boredom can be balanced by an organizational supervisory structure that promotes employee involvement and control over tasks, and job enlargement that introduces task variety. The social conditions of VDU work could be improved by balancing the loads that are potentially stressful and by considering all of the work elements and their potential for promoting or reducing stress. The organizational structure itself could be adapted to accommodate enriched jobs in order to provide support to the individual. Increased staffing levels, increasing the levels of shared responsibilities or increasing the financial resources put toward worker well-being are other possible solutions.



Additional Info

Read 6296 times Last modified on Thursday, 13 October 2011 18:24

" DISCLAIMER: The ILO does not take responsibility for content presented on this web portal that is presented in any language other than English, which is the language used for the initial production and peer-review of original content. Certain statistics have not been updated since the production of the 4th edition of the Encyclopaedia (1998)."


Part I. The Body
Part II. Health Care
Part III. Management & Policy
Part IV. Tools and Approaches
Part V. Psychosocial and Organizational Factors
Part VI. General Hazards
Barometric Pressure Increased
Barometric Pressure Reduced
Biological Hazards
Disasters, Natural and Technological
Heat and Cold
Hours of Work
Indoor Air Quality
Indoor Environmental Control
Radiation: Ionizing
Radiation: Non-Ionizing
Visual Display Units
Part VII. The Environment
Part VIII. Accidents and Safety Management
Part IX. Chemicals
Part X. Industries Based on Biological Resources
Part XI. Industries Based on Natural Resources
Part XII. Chemical Industries
Part XIII. Manufacturing Industries
Part XIV. Textile and Apparel Industries
Part XV. Transport Industries
Part XVI. Construction
Part XVII. Services and Trade
Part XVIII. Guides

Visual Display Units References

Akabri, M and S Konz. 1991. Viewing distance for VDT work. In Designing For Everyone, edited by Y Queinnec and F Daniellou. London: Taylor & Francis.

Apple Computer Co. 1987. Apple Human Interface Guidelines. The Apple Desktop Interface. Waltham, Mass.: Addison-Wesley.

Amick, BC and MJ Smith. 1992. Stress, computer-based work monitoring and measuring systems: A conceptual overview. Appl Ergon 23(1):6-16.

Bammer, G. 1987. How technologic change can increase the risk of repetitive motions injuries. Seminars Occup Med 2:25-30.

—. 1990. Review of current knowledge -Musculoskeletal problems. In Work With Display Units 89: Selected Papers from the Work with Display Units Conference, September 1989, Montreal, edited by L Berlinguet and D Berthelette. Amsterdam: North Holland.

Bammer, G and B Martin. 1988. The arguments about RSI: An examination. Community Health Stud 12:348-358.

—. 1992. Repetition strain injury in Australia: Medical knowledge, social movement and de facto partisanship. Social Prob 39:301-319.

Bastien, JMC and DL Scapin. 1993. Ergonomic criteria for the evaluation of human-computer interfaces. Technical Report no. 156, Programme 3 Artificial Intelligence, cognitive systems, and man-machine interaction. France: INRIA.

Berg, M. 1988. Skin problems in workers using visual display terminals: A study of 201 patients. Contact Dermat 19:335-341.

—-. 1989. Facial skin complaints and work at visual display units. Epidemiological, clinical and histopathological studies. Acta Derm-Venereol Suppl. 150:1-40.

Berg, M, MA Hedblad, and K Erkhardt. 1990. Facial skin complaints and work at visual display units: A histopathological study. Acta Derm-Venereol 70:216-220.

Berg, M, S Lidén, and O Axelson. 1990. Skin complaints and work at visual display units: An epidemiological study of office employees. J Am Acad Dermatol 22:621-625.

Berg, M, BB Arnetz, S Lidén, P Eneroth, and A Kallner. 1992. Techno-stress, a psychophysiological study of employees with VDU-associated skin complaints. J Occup Med 34:698-701.

Bergqvist, U. 1986. Pregnancy and VDT work -An evaluation of the state of the art. In Work With Display Units 86: Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Bikson, TK. 1987. Understanding the implementation of office technology. In Technology and the Transformation of White-Collar Work, edited by RE Kraut. Hillsdale, NJ: Erlbaum Associates.

Bjerkedal, T and J Egenaes. 1986. Video display terminals and birth defects. A study of pregnancy outcomes of employees of the Postal-Giro-Center, Oslo, Norway. In Work With Display Units 86: Selected Papers from the Interantional Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Blackwell, R and A Chang. 1988. Video display terminals and pregnancy. A review. Brit J Obstet Gynaec 95:446-453.

Blignault, I. 1985. Psychosocial aspects of occupational overuse disorders. Master of Clinical Psychology Thesis, Department of Psychology, The Australian National University, Canberra ACT.

Boissin, JP, J Mur, JL Richard, and J Tanguy. 1991. Study of fatigue factors when working on a VDU. In Designing for Everyone, edited by Y Queinnec and F Daniellou. London: Taylor & Francis.

Bradley, G. 1983. Effects of computerization on work environment and health: From a perspective of equality between sexes. Occup Health Nursing :35-39.

—. 1989. Computers and the Psychological Environment. London: Taylor & Francis.
Bramwell, RS and MJ Davidson. 1994. Visual display units and pregnancy outcome: A prospective study. J Psychosom Obstet Gynecol 14(3):197-210.

Brandt, LPA and CV Nielsen. 1990. Congenital malformations among children of women working with video display terminals. Scand J Work Environ Health 16:329-333.

—. 1992. Fecundity and the use of video display terminals. Scand J Work Environ Health 18:298-301.

Breslow, L and P Buell. 1960. Mortality and coronary heart disease and physical activity on work in California. J Chron Dis 11:615-626.

Broadbeck, FC, D Zapf, J Prumper, and M Frese. 1993. Error handling in office work with computers: A field study. J Occup Organ Psychol 66:303-317.

Brown, CML. 1988. Human-Computer Interface Guidelines. Norwood, NJ: Ablex.

Bryant, HE and EJ Love. 1989. Video display terminal use and spontaneous abortion risk. Int J Epidemiol 18:132-138.

Çakir, A. 1981. Belastung und Beanspruching bei Biuldschirmtätigkeiten. In Schriften zur Arbeitspychologie, edited by M Frese. Bern: Huber.

Çakir, A, D Hart, and TFM Stewart. 1979. The VDT Manual. Darmstadt: Inca-Fiej Research Association.

Carayon, P. 1993a. Job design and job stress in office workers. Ergonomics 36:463-477.

—. 1993b. Effect of electronic performance monitoring on job design and worker stress: A review of the literature and conceptual model. Hum Factors 35(3):385-396.

Carayon-Sainfort, P. 1992. The use of computers in offices: Impact on task characteristics and worker stress. Int J Hum Comput Interact 4:245-261.

Carmichael, AJ and DL Roberts. 1992. Visual display units and facial rashes. Contact Dermat 26:63-64.

Carroll, JM and MB Rosson. 1988. Paradox of the active user. In Interfacing Thought. Cognitive Aspects of Human-Computer Interaction, edited by JM Carroll. Cambridge: Bradford.

Cohen, ML, JF Arroyo, GD Champion, and CD Browne. 1992. In search of the pathogenesis of refractory cervicobrachial pain syndrome. A deconstruction of the RSI phenomenon. Med J Austral 156:432-436.

Cohen, S and N Weinstein. 1981. Nonauditory effects of noise on behavior and health. J Soc Issues 37:36-70.

Cooper, CL and J Marshall. 1976. Occupational sources of stress: A review of the literature relating to coronary heart disease and mental ill health. J Occup Psychol 49:11-28.

Dainoff, MG. 1982. Occupational Stress Factors in VDT Operation: A Review of Empirical Research in Behavior and Information Technology. London: Taylor & Francis.

Desmarais, MC, L Giroux, and L Larochelle. 1993. An advice-giving interface based on plan-recognition and user-knowledge assessment. Int J Man Mach Stud 39:901-924.

Dorard, G. 1988. Place et validité des tests ophthalmologiques dans l’étude de la fatigue visuelle engendrée par le travail sur écran. Grenoble: Faculté de médecine, Univ. de Grenoble.

Egan, DE. 1988. Individual differences in human-computer interaction. In Handbook of Human-Computer Interaction, edited by M Helander. Amsterdam: Elsevier.

Ellinger, S, W Karmaus, H Kaupen-Haas, KH Schäfer, G Schienstock, and E Sonn. 1982. 1982 Arbeitsbedingungen, gesundheitsverhalten und rheumatische Erkrankungen. Hamburg: Medizinische Soziologie, Univ. Hamburg.

Ericson, A and B Källén. 1986. An epidemiological study of work with video screens and pregnancy outcome: II. A case-control study. Am J Ind Med 9:459-475.

Frank, AL. 1983. Effects of Health Following Occupational Exposure to Video Display Terminals. Lexington, Ky: Department of Preventive Medicine and Environmental Health.

Frese, M. 1987. Human-computer interaction in the office. In International Review of Industrial and Organizational Psychology, edited by CL Cooper. New York: Wiley.

Frölén, H and N-M Svedenstål. 1993. Effects of pulsed magnetic fields on the developing mouse embryo. Biolelectromagnetics 14:197-204.

Fry, HJH. 1992. Overuse syndrome and the Overuse concept. Discussion Papers On the Pathology of Work-Related Neck and Upper Limb Disorders and the Implications for Treatment, edited by G Bammer. Working paper No. 32. Canberra: NCEPH, Australian National Univ.

Gaines, BR and MLG Shaw. 1986. From timesharing to the sixth generation: The development of human-computer interaction. Part I. Int J Man Mach Stud 24:1-27.

Gardell, B. 1971. Alienation and mental health in the modern industrial environment. In Society, Stress, and Disease, edited by L Levi. Oxford: OUP.

Goldhaber, MK, MR Polen, and RA Hiatt. 1988. The risk of miscarriage and birth defects among women who use visual display terminals during pregnancy. Am J Ind Med 13:695-706.

Gould, JD. 1988. How to design usable systems. In Handbook of Human Computer Interaction, edited by M Helander. Amsterdam: Elsevier.

Gould, JD and C Lewis. 1983. Designing for usability—Key principles and what designers think. In Proceedings of the 1983 CHI Conference On Human Factors in Computing Systems, 12 December, Boston. New York: ACM.

Grandjean, E. 1987. Ergonomics in Computerized Offices. London: Taylor & Francis.

Hackman, JR and GR Oldham. 1976. Motivation through the design of work: Test of a theory. Organ Behav Hum Perform 16:250-279.

Hagberg, M, Å Kilbom, P Buckle, L Fine, T Itani, T Laubli, H Riihimaki, B Silverstein, G Sjogaard, S Snook, and E Viikari-Juntura. 1993. Strategies for prevention of work-related musculo-skeletal disorders. Appl Ergon 24:64-67.

Halasz, F and TP Moran. 1982. Analogy considered harmful. In Proceedings of the Conference On Human Factors in Computing Systems. Gaithersburg, Md.: ACM Press.

Hartson, HR and EC Smith. 1991. Rapid prototyping in human-computer interface development. Interact Comput 3(1):51-91.

Hedge, A, WA Erickson, and G Rubin. 1992. Effects of personal and occupational factors on sick building syndrome reports in air-conditioned offices. In Stress and Well-Being At Work-Assessments and Interventions for Occcupational Mental Health, edited by JC Quick, LR Murphy, and JJ Hurrell Jr. Washington, DC: American Psychological Association.

Helme, RD, SA LeVasseur, and SJ Gibson. 1992. RSI revisited: Evidence for psychological and physiological differences from an age, sex and occupation matched control group. Aust NZ J Med 22:23-29.

Herzberg, F. 1974. The wise old Turk. Harvard Bus Rev (Sept./Oct.):70-80.

House, J. 1981. Work Stress and Social Support. Reading, Mass.: Addison-Wesley.

Hutchins, EL. 1989. Metaphors for interactive systems. In The Structure of Multimodal Dialogue, edited by DG Bouwhuis, MM Taylor, and F Néel. Amsterdam: North Holland.

Huuskonen, H, J Juutilainen, and H Komulainen. 1993. Effects of low-frequency magnetic fields on fetal development in rats. Biolelectromagnetics 14(3):205-213.

Infante-Rivard, C, M David, R Gauthier, and GE Rivard. 1993. Pregnancy loss and work schedule during pregnancy. Epidemiology 4:73-75.

Institut de recherche en santé et en sécurité du travail (IRSST). 1984. Rapport du groupe de travail sur les terminaux è écran de visualisation. Montréal: IRSST.

International Business Machines Corp. (IBM). 1991a. Systems Application Architecture. Common User Access Guide-Advanced Interface Design Reference. White Plains, NY.: IBM.

—. 1991b. Systems Application Architecture. Common User Access Guide to User Interface Design. White Plains, NY.: IBM.

International Labour Organization (ILO). 1984. Automation, Work Organisation and Occupational Stress. Geneva: ILO.

—. 1986. Special issue on visual display units. Cond Work Dig .

—. 1989. Working with Visual Display Units. Occupational Safety and Health Series, No. 61. Geneva: ILO.

—. 1991. Worker’s privacy. Part I: Protection of personal data. Cond Work Dig 10:2.

International Organization for Standardization (ISO). 1992. Ergonomic Requirements for Office Work With Visual Display Terminals (VDTs). ISO Standard 9241.Geneva: ISO.

Johansson, G and G Aronsson. 1984. Stress reactions in computerized administrative work. J Occup Behav 5:159-181.

Juliussen, E and K Petska-Juliussen. 1994. The Seventh Annual Computer Industry 1994-1995 Almanac. Dallas: Computer Industry Almanac.

Kalimo, R and A Leppanen. 1985. Feedback from video display terminals, performance control and stress in text preparation in the printing industry. J Occup Psychol 58:27-38.

Kanawaty, G. 1979. Introduction to Work Study. Geneva: ILO.

Karasek, RA, D Baker, F Marxer, A Ahlbom, and R Theorell. 1981. Job decision latitude, job demands, and cardiovascular disease. In Machine-Pacing and Occupational Stress, edited by G Salvendy and MJ Smith. London: Taylor & Francis.

Karat, J. 1988. Software evaluation methodologies. In Handbook of Human-Computer Interaction, edited by M Helander. Amsterdam: Elsevier.

Kasl, SV. 1978. Epidemiological contributions to the study of work stress. In Stress At Work, edited by CL Cooper and R Payne. New York: Wiley.

Koh, D, CL Goh, J Jeyaratnam, WC Kee, and CN Ong. 1991. Dermatologic complaints among visual display unit operators and office workers. Am J Contact Dermatol 2:136-137.

Kurppa, K, PC Holmberg, K Rantala, T Nurminen, L Saxén, and S Hernberg. 1986. Birth defects, course of pregnancy, and work with video display units. A Finnish case-referent study. In Work With Display Units 86: Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Läubli, T, H Nibel, C Thomas, U Schwanninger, and H Krueger. 1989. Merits of periodic visual screening tests in VDU operators. In Work With Computers, edited by MJ Smith and G Salvendy. Amsterdam: Elsevier Science.

Levi, L. 1972. Stress and Distress in Response to Psychosocial Stimuli. New York: Pergamon Press.

Lewis, C and DA Norman. 1986. Designing for error. In User Centered System: New Perspectives On Human-Computer Interation, edited by DA Norman and SW Draper. Hillsdale, NJ.: Erlbaum Associates.

Lidén, C. 1990. Contact allergy: A cause of facial dermatitis among visual display unit operators. Am J Contact Dermatol 1:171-176.

Lidén, C and JE Wahlberg. 1985. Work with video display terminals among office employees. Scand J Work Environ Health 11:489-493.

Lindbohm, M-L, M Hietanen, P Kygornen, M Sallmen, P von Nandelstadh, H Taskinen, M Pekkarinen, M Ylikoski, and K Hemminki. 1992. Magnetic fields of video display terminals and spontaneous abortion. Am J Epidemiol 136:1041-1051.

Lindström, K. 1991. Well-being and computer-mediated work of various occupational groups in banking and insurance. Int J Hum Comput Interact 3:339-361.

Mantei, MM and TJ Teorey. 1989. Incorporating behavioral techniques into the systems development life cycle. MIS Q September:257-274.

Marshall, C, C Nelson, and MM Gardiner. 1987. Design guidelines. In Applying Cognitive Psychology to User-Interface Design, edited by MM Gardiner and B Christie. Chichester, UK: Wiley.

Mayhew, DJ. 1992. Principles and Guidelines in Software User Interface Design. Englewood Cliffs, NJ.: Prentice Hall.

McDonald, AD, JC McDonald, B Armstrong, N Cherry, AD Nolin, and D Robert. 1988. Work with visual display units in pregnancy. Brit J Ind Med 45:509-515.

McGivern, RF and RZ Sokol. 1990. Prenatal exposure to a low-frequency electromagnetic field demasculinizes adult scent marking behavior and increases accessory sex organ weights in rats. Teratology 41:1-8.

Meyer, J-J and A Bousquet. 1990. Discomfort and disability glare in VDT operators. In Work With Display Units 89, edited by L Berlinguet and D Berthelette. Amsterdam: Elsevier Science.

Microsoft Corp. 1992. The Windows Interface: An Application Design Guide. Redmond, Wash.: Microsoft Corp.

Monk, TH and DI Tepas. 1985. Shift work. In Job Stress and Blue Collar Work, edited by CL Cooper and MJ Smith. New York: Wiley.

Moran, TP. 1981. The command language grammar: A representation for the user interface of interaction computer systems. Int J Man Mach Stud 15:3-50.

—-. 1983. Getting into a system: External-internal task mapping analysis. In Proceedings of the 1983 CHI Conference On Human Factors in Computing Systems, 12-15 December, Boston. New York: ACM.

Moshowitz, A. 1986. Social dimensions of office automation. Adv Comput 25:335-404.

Murray, WE, CE Moss, WH Parr, C Cox, MJ Smith, BFG Cohen, LW Stammerjohn, and A Happ. 1981. Potential Health Hazards of Video Display Terminals. NIOSH Research Report 81-129. Cincinnati, Ohio: National Institute for Occupational Safety and Health (NIOSH).

Nielsen, CV and LPA Brandt. 1990. Spontaneous abortion among women using video display terminals. Scand J Work Environ Health 16:323-328.

—-. 1992. Fetal growth, preterm birth and infant mortality in relation to work with video display terminals during pregnancy. Scand J Work Environ Health 18:346-350.

Nielsen, J. 1992. The usability engineering life cycle. Computer (Mar.):12-22.

—-. 1993. Iterative user-interface design. Computer (Nov.):32-41.

Nielsen, J and RL Mack. 1994. Usability Inspection Methods. New York: Wiley.

Numéro spécial sur les laboratoires d’utilisabilité. 1994. Behav Inf Technol.

Nurminen, T and K Kurppa. 1988. Office employment, work with video display terminals, and course of pregnancy. Reference mothers’ experience from a Finnish case-referent study of birth defects. Scand J Work Environ Health 14:293-298.

Office of Technology Assessment (OTA). 1987. The Electronic Supervisor: New Technology, New Tensions. Washington, DC: US Government Printing Office.

Open Software Foundation. 1990. OSF/Motif Style Guide. Englewood Cliffs, NJ: Prentice Hall.

Ostberg, O and C Nilsson. 1985. Emerging technology and stress. In Job Stress and Blue Collar Work, edited by CL Cooper and MJ Smith. New York: Wiley.

Piotrkowski, CS, BFG Cohen, and KE Coray. 1992. Working conditions and well-being among women office workers. Int J Hum Comput Interact 4:263-282.

Pot, F, P Padmos, and A Brouwers. 1987. Determinants of the VDU operator’s well-being. In Work With Display Units 86. Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Preece, J, Y Rogers, H Sharp, D Benyon, S Holland, and T Carey. 1994. Human Computer Interaction. Reading, Mass.: Addison-Wesley.

Quinter, J and R Elvey. 1990. The neurogenic hypothesis of RSI. Discussion Papers On the Pathology of Work-Related Neck and Upper Limb Disorders and the Implications for Treatment, edited by G Bammer. Working paper No. 24. Canberra: NCEPH, Australian National Univ.

Rasmussen, J. 1986. Information Processing and Man-Machine Interaction. An Approach to Cognitive Engineering. New York: North Holland.

Ravden, SJ and GI Johnson. 1989. Evaluating Usability of Human-Computer Interfaces: A Practical Approach. West Sussex, UK: E Horwood.

—. 1992. Systems Application Architecture: Common Communications Support. Englewood Cliffs, NJ: Prentice Hall.

Reed, AV. 1982. Error correcting strategies and human interaction with computer systems. In Proceedings of the Conference On Human Factors in Computing Systems Gaithersburg, Md.: ACM.

Rey, P and A Bousquet. 1989. Visual strain of VDT operators: The right and the wrong. In Work With Computers, edited by G Salvendy and MJ Smith. Amsterdam: Elsevier Science.

—. 1990. Medical eye examination strategies for VDT operators. In Work With Display Units 89, edited by L Berlinguet and D Berthelette. Amsterdam: Elsevier Science.

Rheingold, HR. 1991. Virtual Reality. New York: Touchstone.

Rich, E. 1983. Users are individuals: Individualizing user models. Int J Man Mach Stud 18:199-214.

Rivas, L and C Rius. 1985. Effects of chronic exposure to weak electromagnetic fields in mice. IRCS Med Sci 13:661-662.

Robert, J-M. 1989. Learning a computer system by unassisted exploration. An example: The Macintosh. In MACINTER II Man-Computer Interaction Research, edited by F Klix, N Streitz, Y Warren, and H Wandke. Amsterdam: Elsevier.

Robert, J-M and J-Y Fiset. 1992. Conception et évaluation ergonomiques d’une interface pour un logiciel d’aide au diagnostic: Une étude de cas. ICO printemps-été:1-7.

Roman, E, V Beral, M Pelerin, and C Hermon. 1992. Spontaneous abortion and work with visual display units. Brit J Ind Med 49:507-512.

Rubino, GF. 1990. Epidemiologic survey of ocular disorders: The Italian multicentric research. In Work With Display Units 89, edited by L Berlinguet and D Berthelette. Amsterdam: Elsevier Science.

Rumelhart, DE and DA Norman. 1983. Analogical processes in learning. In Cognitive Skills and Their Acquisition, edited by JR Anderson. Hillsdale, NJ: Lawrence Erlbaum.

Ryan, GA and M Bampton. 1988. Comparison of data process operators with and without upper limb symptoms. Community Health Stud 12:63-68.

Ryan, GA, JH Mullerworth, and J Pimble. 1984. The prevalence of repetition strain injury in data process operators. In Proceedings of the 21st Annual Conference of the Ergonomics Society of Australia and New Zealand. Sydney.

Sainfort, PC. 1990. Job design predictors of stress in automated offices. Behav Inf Technol 9:3-16.

—-. 1991. Stress, job control and other job elements: A study of office workers. Int J Ind Erg 7:11-23.

Salvendy, G. 1992. Handbook of Industrial Engineering. New York: Wiley.

Salzinger, K and S Freimark. 1990. Altered operant behavior of adult rats after perinatal exposure to a 60-Hz electromagnetic field. Biolelectromagnetics 11:105-116.

Sauter, SL, CL Cooper, and JJ Hurrell. 1989. Job Control and Worker Health. New York: Wiley.

Sauter, SL, MS Gottlieb, KC Jones, NV Dodson, and KM Rohrer. 1983a. Job and health implications of VDT use: Initial results of the Wisconsin-NIOSH study. Commun ACM 26:284-294.

Sauter, SL, MS Gottlieb, KM Rohrer, and NV Dodson. 1983b. The Well-Being of Video Display Terminal Users. An Exploratory Study. Cincinnati, Ohio: NIOSH.

Scapin, DL. 1986. Guide ergonomique de conception des interfaces homme-machine. Rapport de recherche no. 77. Le Chesnay, France: INRIA.

Schnorr, TM, BA Grajewski, RW Hornung, MJ Thun, GM Egeland, WE Murray, DL Conover, and WE Halperin. 1991. Video display terminals and the risk of spontaneous abortion. New Engl J Med 324:727-733.

Shepherd, A. 1989. Analysis and training in information technology tasks. In Task Analysis for Human-Computer Interaction, edited by D Diaper. Chichester: E Horwood.

Shneiderman, B. 1987. Designing the User Interface: Strategies for Effective Human-Computer Interaction. Reading, Mass.: Addison-Wesley.

Sjödren, S and A Elfstrom. 1990. Eye discomfort among 4000 VDU users. In Work With Display
Units 89, edited by L Berlinguet and D Berthelette. Amsterdam: Elsevier Science.

Smith, MJ. 1987. Occupational stress. In Handbook of Ergonomics/Human Factors, edited by G Salvendy. New York: Wiley.

Smith, MJ and BC Amick. 1989. Electronic monitoring at the workplace: Implications for employee control and job stress. In Job Control and Worker Health, edited by S Sauter, J Hurrel, and C Cooper. New York: Wiley.

Smith, MJ, P Carayon, and K Miezio. 1987. VDT technology: Psychosocial and stress concerns. In Work With Display Units, edited by B Knave and PG Widebäck. Amsterdam: Elsevier Science.

Smith, MJ and P Carayon-Sainfort. 1989. A balance theory of job design for stress reduction. Int J Ind Erg 4:67-79.

Smith, MJ, BFG Cohen, LW Stammerjohn, and A Happ. 1981. An investigation of health complaints and job stress in video display operations. Hum Factors 23:387-400.

Smith, MJ, P Carayon, KH Sanders, S-Y Lim, and D LeGrande. 1992a. Electronic performance monitoring, job design and worker stress. Appl Ergon 23:17-27.

Smith, MJ, G Salvendy, P Carayon-Sainfort, and R Eberts. 1992b. Human-computer interaction. In Handbook of Industrial Engineering, edited by G Salvendy. New York: Wiley.

Smith, SL and SL Mosier. 1986. Guidelines for Designing User Interface Software. Report ESD-TR-278. Bedford, Mass.: MITRE.

South Australian Health Commission Epidemiology Branch. 1984. Repetition Strain Symptoms and Working Conditions Among Keyboard Workers Engaged in Data Entry or Word Processing in the South Australian Public Service. Adelaide: South Australian Health Commission.

Stammerjohn, LW, MJ Smith, and BFG Cohen. 1981. Evaluation of work station design factors in VDT operations. Hum Factors 23:401-412.

Stellman, JM, S Klitzman, GC Gordon, and BR Snow. 1985. Air quality and ergonomics in the office: Survey results and methodologic issues. Am Ind Hyg Assoc J 46:286-293.

—-. 1987a. Comparison of well-being among non-machine interactive clerical workers and full-time and part-time VDT users and typists. In Work With Display Units 86. Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

—-. 1987b. Work environment and the well-being of clerical and VDT workers. J Occup Behav 8:95-114.

Strassman, PA. 1985. Information Payoff: The Transformation of Work in the Electronic Age. New York: Free Press.

Stuchly, M, AJ Ruddick, et al. 1988. Teratological assessment of exposure to time-varying magnetic fields. Teratology 38:461-466.

Sun Microsystems Inc. 1990. Open Look. Graphical User Interface Application Style Guidelines. Reading, Mass.: Addison-Wesley.

Swanbeck, G and T Bleeker. 1989. Skin problems from visual display units: Provocation of skin symptoms under experimental conditions. Acta Derm-Venereol 69:46-51.

Taylor, FW. 1911. The Principles of Scientific Management. New York: Norton & Co.

Thimbleby, H. 1990. User Interface Design. Chichester: ACM.

Tikkanen, J and OP Heinonen. 1991. Maternal exposure to chemical and physical factors during pregnancy and cardiovascular malformations in the offspring. Teratology 43:591-600.

Tribukait, B and E Cekan. 1987. Effects of pulsed magnetic fields on embryonic development in mice. In Work With Display Units 86: Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Wahlberg, JE and C Lidén. 1988. Is the skin affected by work at visual display terminals? Dermatol Clin 6:81-85.

Waterworth, JA and MH Chignell. 1989. A manifesto for hypermedia usability research. Hypermedia 1:205-234.

Westerholm, P and A Ericson. 1986. Pregnancy outcome and VDU work in a cohort of insurance clerks. In Work With Display Units 86. Selected Papers from the International Scientific Conference On Work With Display Units, May 1986, Stockholm, edited by B Knave and PG Widebäck. Amsterdam: North Holland.

Westlander, G. 1989. Use and non-use of VDTs—Organization of terminal work. In Work With Computers: Organizational, Management, Stress and Health Aspects, edited by MJ Smith and G Salvendy. Amsterdam: Elsevier Science.

Westlander, G and E Aberg. 1992. Variety in VDT work: An issue for assessment in work environment research. Int J Hum Comput Interact 4:283-302.

Wickens, C. 1992. Engineering Psychology and Human Performance. New York: Harper Collins.

Wiley, MJ and P Corey. 1992. The effects of continuous exposure to 20-khz sawtooth magnetic fields on the litters of CD-1 mice. Teratology 46:391-398.

Wilson, J and D Rosenberg. 1988. Rapid prototyping for user interface design. In Handbook of Human-Computer Interaction, edited by M Helander. Amsterdam: Elsevier.

Windham, GC, L Fenster, SH Swan, and RR Neutra. 1990. Use of video display terminals during pregnancy and the risk of spontaneous abortion, low birthweight, or intrauterine growth retardation. Am J Ind Med 18:675-688.

World Health Organization (WHO). 1987. Visual Display Terminals and Workers’ Health. Geneva: WHO.

—-. 1989. Work with visual display terminals: Psychosocial aspects and health. J Occup Med 31:957-968.

Yang, C-L and P Carayon. 1993. Effects of job demands and job support on worker stress: A study of VDT users. Behav Inf Technol .

Young, JE. 1993. Global Network. Computers in a Sustainable Society. Washington, DC: Worldwatch Paper 115.

Young, RM. 1981. The machine inside the machine: Users’ models of pocket calculators. Int J Man Mach Stud 15:51-85.

Zecca, L, P Ferrario, and G Dal Conte. 1985. Toxicological and teratological studies in rats after exposure to pulsed magnetic fields. Bioelectrochem Bioenerget 14:63-69.

Zuboff, S. 1988. In the Age of the Smart Machine: The Future of Work and Power. New York: Basic Books.