The Impact of System Response Time on Navigating through Hypertext

Two experiments investigated the effects of system response time (SRT) on navigating through hypertext. SRT duration was varied systematically and manipulated between subjects. The dependent variables were residence time, emotional strain, and memory performance. All three variables were influenced by SRT. As a prominent result, a synchronization between computer’s and human’s response time was observed. In descriptive terms, the distinguishing feature of browsing a hypertext database is that the user accesses the linked elements in an order of his own choice. To formalize this process, two temporal components can be identified. First, there is the technology-induced time of the transmitting a requested document from the server to the user’s workstation. This time span is referred to as system response time (SRT). Second, there is the user-determined period of perception and engagement with the requested document. This period, during which a multitude of actions and decisions may occur, is collectively called residence time. It could be assumed that residence time and SRT are independent of one another. However, research in software engineering and ergonomics clearly contradicts such an assumption. It turns out that not only too long SRT, but also too short SRT has serious effects on human-computer interaction. On the one hand, work productivity and satisfaction decreases as SRT increases. On the other hand, there is also evidence that very short delays may induce an agitated work style, leading to a reduction in performance accuracy (Barber, 1983; Boucsein, 1987; Kohlisch & Kuhmann, 1997; Miller, 1968). Shneiderman (1984) explained the agitated work style by the user’s tendency to adopt the work speed of the system. Two experiments manipulated SRT levels to investigate if these phenomena occur in browsing a hypertext interface to a large and homogeneous database consisting of entertaining pictorial material.