Date of Award

Summer 1996

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Glynn D. Coates

Committee Member

Raymond H. Kirby

Committee Member

J. Raymond Comstock, Jr.


Performance was evaluated under varying levels of time pressure and information load to determine their influence on simple rule-based decision-making. Consistent errors, biases, and heuristics found in human decision-making have been attributed to attempts to reduce attentional demands and to the limitations of working memory. Do these same mistakes occur when little or no demand is placed on working memory and the decision is made by following a set of simple rules? Using a simulation of a radar operator's task, 96 participants monitored a display for 24 min. Time pressure was manipulated by increasing or decreasing the number of aircraft to be monitored. Information load was controlled by the amount of information required to make a decision on whether the aircraft was a "friend" or an "enemy." Increases in time pressure resulted in a decrease in reaction time (RT) and an increase in the percent of aircraft identified correctly until the highest level of stress where RT increased and percent of aircraft correctly identified decreased. Increases in information load resulted in longer RT and a decline in the percent of correct identifications in three of the four conditions. In general, performance improved as time pressure increased rather than decreased over the task. Overall, performance was best under low levels of information load, moderate levels of time pressure, and when the task progressed from low-to-high levels of time pressure, rather than the reverse. Support was found for anchoring or confirmation bias.


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