The Effects of Screen Size, Information Organization, and Time on User Comprehension of Text-Based Information Presented in a Web Browser
Lawrence E. Burgee, Ph.D., University of Maryland, Baltimore County, 2005
The growth of the Web has resulted in massive stores of informational Web pages, accessed using personal computer visual display units (VDUs) and Web browsers. Personal digital assistants (PDAs) with small screens can have Internet connections and Web browsers. Web pages can contain hypertext allowing users to process materials sequentially or through hyperlinks. Time constraints can affect comprehension of information retrieval tasks. Students are increasingly using small handheld computing devices to access Web information and it is important to assess their comprehension. This dissertation explores large-screen and small-screen VDUs and the effects on user accuracy and completion time when completing sequential and hypertext information retrieval tasks using a browser under various time constraints. Ninety-two subjects each completed sixteen reading tasks in which they were exposed to all combinations of screen size, information organization, and time constraints. The general linear model was used for treatment comparisons and significance tests. Subjects completed a post-test questionnaire in which demographic, experience, and preference data were collected.
For screen size, the results suggest that comprehension and performance are superior on a large-screen VDU as compared to a small-screen VDU for the processing of browser-based textual information. Designers should develop small-screen browser content that specifically addresses the reduced screen and character sizes and greater paging and scrolling requirements. This can be done by strengthening the fixity of the information and improving sense of text. For information organization, the results suggest that comprehension is equivalent but that performance is superior for sequential tasks as compared to hypertext tasks. Browser content designed to be read in sequential order should limit hypertext to minimize distraction. Hypertext should be carefully encoded because readers will ignore available hypertext cues in order to stay focused on reading. For time constraints, the results suggest that comprehension and performance are superior for low-time-pressure treatments as compared to moderate-time-pressure treatments. To compensate for increased time pressure, subjects become more selective when answering questions. It was discovered that extensive prior experience and good proficiency with personal computers, browsers, and cellphones, helped subjects competently use PDAs, devices that most subjects had never used before.