HUMAN–COMPUTER INTERACTION:ITERATIVE DESIGN

ITERATIVE DESIGN

Interactive systems are meant to make work more effective and efficient so that employees can be productive, satisfied, and healthy. Good design improves the motivation of employees to work toward the betterment of the employer. The consideration of ergonomic, cognitive, social, organizational, and management factors of interactive system design must be recognized as an iterative design process. By considering these factors in an iterative manner, system designs can evolve until the desired level of performance and safety are achieved. Additional modifications and resources expen- diture will then be unnecessary. This allows valuable resources to be saved or applied to other endeavors. Table 14 provides a list of general guidelines as to how these factors can be designed to create an effective, productive, healthy, and satisfying work environment.

The concept of balance is very important in managing the design, introduction, and use of com- puter technologies (Smith and Sainfort 1989). Negative effects or influences can be counteracted by positive aspects. For instance, if the physical design of the technology cannot be changed and is known to be flawed, decision makers and users could counteract the negative influences of such design by, for instance, providing more control over the work–rest schedule. By having control over their work–rest schedule, workers could relieve some of the physical stresses imposed by the tech- nology by moving around. If management expects layoffs due to the introduction of computers, actions should be taken to ensure that workers are aware of these changes. Sharing information and getting valuable training or skills could be positive ways to counteract the negative effects linked to layoff. Carayon (1994) has shown that office and computer jobs can be characterized by positive and negative aspects and that different combinations of positive and negative aspects are related to dif- ferent strain outcomes. A job with high job demands, but positive aspects such as skill utilization, task clarity, job control and social support, led to low boredom and a medium level of daily life stress. A job with many negative aspects of work led to high boredom, workload dissatisfaction, and daily life stress.

Another important aspect of the iterative design process is time. Changes in the workplace occur at an increasing pace, in particular with regard to computer technology. The term continuous change has been used to characterize the fast and frequent changes in computer technology and its impact on people and organizations (Korunka et al. 1997; Korunka and Carayon 1999). The idea behind this is that technological change is rarely, if ever, a one-time shot. Typically, technology changes are closer to continuous rather than discrete events. This is because rapid upgrades and reconfigurations to make the systems work more effectively are usually ongoing. In addition to technological changes, time has other important effects on the entire work system (Carayon 1997). In particular, the aspects of the computerized work system that affect people may change over time. In a longitudinal study

of computer users, Carayon and her colleagues have shown that the job characteristics related to worker strain change over time (Carayon et al. 1995). Therefore, any iterative design strategy for improving the design of interactive systems should take into account temporal factors.

The idea of balancing the negative aspects of the work system by the positive aspects implies an active role from the part of all actors involved in the process. An active role characterized by infor- mation gathering, planning, and looking for alternatives can be much more effective than a passive role in achieving efficient use of computer technologies (Haims and Carayon 1998; Wilson and Haines 1997).

This chapter has presented information and data on how to design human–computer interfaces effectively from the physical, cognitive, and social points of view. Each of these has been presented separately, but there is a definite interaction among these three aspects. For example, Eberts et al. (1990) concluded that in group computer work, when the job design was enriched, the individuals in the group better understood the other group members’ cognitive style than when the job was simplified. The better understanding resulted in more effective group performance than when the cognitive styles of other group members were less understood. This illustrates an interaction effect between social and cognitive factors in human–computer interaction.

The effects of physical and cognitive interaction in human–computer interaction have been doc- umented by Karwowski et al. (1994). They demonstrated, as a result of a highly controlled study in computer-based mail sorting, that the mode of information presentation on a computer screen and the cognitive response requirement of the user affected and changed their physical posture. Thus, if designers consider both factors in interactive system design they can optimize their interaction.

Cook and Salvendy (1999) have documented, in computer-based work, the interrelationship be- tween social and cognitive factors. They found that increased job enrichment and increased mental workload are some of the most important variables affecting job satisfaction. This raises an interesting dilemma for designers since the cognitive scientist would argue to minimize or optimize mental workload in order to minimize training time and maximize performance. The industrial engineer would argue for minimizing mental workload because that simplifies the work and thus decreases the rate of pay that a company needs to pay for the job. And the social scientist would argue that increasing the mental workload on the job would result in increased job satisfaction. The increased job satisfaction would, in turn, be expected to yield decreased labor turn over and decreased absen- teeism, frequently resulting in increased productivity.

These interactions illustrate the type of dilemmas system developers can encounter during inter- active system design. Involving a multidisciplinary team in the development process allows such opposing requirements to be addressed better. The team must be supported by ergonomists who understand physical requirements, human factors engineers who understand cognitive requirements, and management that believes in the competitive edge that can be gained by developing user-centered interactive systems. Close collaboration among these team members can lead to the development of remarkably effective and highly usable systems that are readily adopted by users.