Download delay, also known as “download time” and “tolerable wait time (TWT),” is the amount of time needed for instructional materials to appear on a Web page on a client computer after the page is accessed from a server. It is a new challenge specific to designing and using Internet-based materials (Davis & Hantula, 2001), but is related to an older mainframe computing difficulty known as system response time (SRT), the time between when a user issues a command and the system responds to the command. Download delay/TWT is primarily a function of the size of the data files being transmitted from the server to the client, the technological limitations of the client and server computers as well as the network infrastructure. A file of equal size may download more slowly or quickly on different client computers, depending on capabilities of the hardware, speed of the network and connections, and relative efficiency in the design of programs and transfer protocols. In an Internet environment with a broadband connection, download delay is usually a matter of seconds, often fractions of a second.
Main Focus: Download Delay
The data on the effects of system response time on the end user are mixed, but appear to point toward an overall negative relation between system response time and user affective reaction; data on actual user performance are much less clear. Emurian (1991) found no link between SRT and performance when examining physiological responses to varying SRTs in video display terminals; Dannenbring (1983) found no effect for system response time on programmer’s performance and satisfaction while debugging programs; on the other hand, Guynes (1998) found that variable system response times and long mean (8.25 seconds) response times in document editing were associated with increased anxiety levels. Schleifer and Amick (1989) found that longer system response time associated with increased mood disturbances in a data entry task, and Barber and Lucas (1983) found that increased system response time was negatively related to user satisfaction with job characteristics, and the system. These negative relations between system response time and affective reactions to the computer system were also found by Wirtz and Bateson (1995) in a study of at-home banking, and by Rushinek and Rushinek (1986), who surveyed more than 4,000 computer users, and found that the single most important variable in satisfaction with the computer system was system response time.
Key Terms in this Chapter
Latency of Feedback/Feedback Latency: The amount of time elapsed between a learner’s response to a prompt or question and the instructor’s or system’s evaluative response to the student.
Client: A computer that downloads files or requests documents or services from a file server.
Kb (Kilobytes): A unit of computer data equal to 1,024 (210) bytes, or more commonly, 1,000 bytes.
Download Delay/Download Time/Total Wait Time: The amount of time needed for elements to appear on a Web page on the client computer after the page is accessed from the server.
User Satisfaction: The overall affective evaluation by an end-user of their experience with a computer or information system; generally measured with a Likert scale.
System Response Time: The amount of time it takes for a computer system to respond to a command from a user.
Server: A computer that processes requests for HTML and other documents or components of Web pages from clients.