The investigation of workplace and computer system characteristics interfering with performance and health is a major topic in human factors research. The field of industrial psychology has been concerned not only with effects of time pressure, heat, noise, and so forth on the worker's emotional and cognitive state, as well as performance, but also with effects of human-computer interaction (e.g., Boucsein, Greif, & Wittenkamp, 1984; Kuhmann, 1989; Kuhmann, Boucsein, Schaefer, & Alexander, 1987; Kuhmann, Schaefer, & Boucsein, 1990; Thum, Boucsein, & Kuhmann, 1995; Trimmel & Huber, 1998; Trimmel, Strassler, & Knerer, 2001). The impact of computer work on subjective occupational stress and health of on psychosomatic symptoms is well documented Johansson & Aronsson, 1984; Pot, Brouwers, & Padmos, 1986; Sauter, Gottlieb, Jones, Dodson, & Rohrer, 1983; Smith, Cohen, Stammerjohn, & Happ, 1981). Psychophysiological stress responses were also observed by Tanaka, Fukomoto, Yamamoto, and Noro (1988) and Gao et al.
(1990) during a simulated data entry task. Several experiments demonstrated that monotonous and repetitive computer work with restricted freedom of decision making led to increased occupational stress (e.g., Frankenhaeuser & Johansson, 1986; Lundberg & Forsman, 1979; Lundberg, Granqvist, Hansson, Magnusson, & Wallin, 1989; Lundberg, Mellin, Evans, & Holmberg, 1993).
One component of human-computer interaction contributing to stress is the system response time (SRT): the time between data input and system response. Some experiments have shown that system response times that are accompanied by uncertainty constitute a major source of stress in human-computer interaction (Shneiderman, 1987).
According to Berlyne (1960), uncertainty causes arousal, as demonstrated by Lovibond (1968), who showed that uncertainty led to unspecific arousal being perceived as aversive. Lovibond further demonstrated that certainty reduced feelings of aversion and also electrodermal responses. Katz and Wykes (1985) examined the effects of predictable and unpredictable electrical stimuli in 80 female participants and demonstrated that predictability reduced stress as measured by electrodermal activity.
Kuhmann et al. (1987) examined the effects of short (2-s) and long (8-s) system response times in a computerized working task. The participants had to perform a simple detection and correction task at a VDT in six trials, each lasting 20 min. Work speed, error rate, and other behavioral as well as psychological and psychophysiological measures were recorded. Concerning performance, results indicated that participants exposed to the long system response time had a lower mean error rate without any difference in working speed. On the physiological level, long SRT led to lower levels of systolic blood pressure and stronger skin conductance reactions. These results are discussed as differential effects of system response times on diverse indicators of stress.
Thum et al. (1995) varied load experimentally to compare the effect of load imposed by task difficulty with that caused by system response time. The authors concluded that both short and long SRTs induced stress. However, psychophysiological responses were attributed to SRT and not to task difficulty. Additionally, these reactions were intensified by the applied time pressure.
Stress caused by SRT in human-computer interaction during the search for information (particularly on the Internet) is a common occurrence and has implications for health and performance. Stress is seen as energy mobilization by negative emotions, over which the affected person has limited control, in contrast to mental load, in which the situation is perceived as challenging (Gaillard & Kramer, 2000). The psychological reason for stress is seen in the lack of control while waiting for the computer to respond. …