Date of Award

Summer 1998

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Glynn D. Coates

Committee Member

James R. Comstock, Jr.

Committee Member

Terry L. Dickinson

Committee Member

Randall L. Harris, Sr.


Information about how operators use their eyes while interacting with visual displays is often an overlooked aspect of human-computer interaction. Such information is fundamental to assessing the quality of software interfaces and understanding the cognitive processes that underlie operator behavior. Other research evaluating information displays evolved from using reaction time and subjective data as dependent variables to using oculometric measures. In the current research conventional performance measures are coupled with oculometric measures to evaluate the influence display characteristics and cognitive variables have on performance.

Twelve subjects used a software program to complete a series of specified tasks. Subjects were asked to search for 36 item from the database in a serial manner. Both keystroke and oculometric data were recorded while the subjects used the software database. Four dependent variables were derived from this data: task time, error rate, dwell time and dwell frequency. The four independent variables were information density, display layout, task complexity, and experience.

Out of the four independent variables used in the current research, task complexity, a cognitive variable, clearly had the largest effect on both the time-based measures of performance and the oculometric measures of performance. Task complexity yielded a main effect in the task time data, the error rate data, the dwell time data and the dwell frequency data. Increases in task complexity yielded increases in task time, error rate, dwell time and dwell frequency. The results also showed that local information density had an effect on task time but only when overall density of the software interface was higher. While it was found that information density had a consistent effect on the frequency of dwells these results support other research that shows information density has a limited effect on performance. The display layout variable also had a limited influence on both performance and oculometric measures.


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