Date of Award

Winter 2013

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Poornima Madhavan

Committee Member

James Bliss

Committee Member

Patrick Hester


The purpose of the current study was to investigate the effects of decision-making strategies and tendencies, time constraint, and signal characteristics on decision-making performance utilizing the fuzzy signal detection theory framework. Participants were tasked with deciding whether x-ray images of passenger luggage contained hazardous objects.

The first objective of the study was to develop a methodology for quantifying optimizing versus satisficing tendencies in decision making through direct measurement and observation.

The second objective of the study was to examine how time constraint and specific signal characteristics contribute to decision making. Interestingly, despite having more time available to conduct a comprehensive search, participants in the global time constraint condition who were able to self-terminate information search tended toward satisficing. They also had shorter overall search durations and greater sensitivities than participants in the local time constraint condition, and had shorter search durations for central compared to eccentric targets. Across time constraint conditions and decision tendencies, participants had greater sensitivities for centrally located targets compared to eccentrically located targets and for ambiguous signals with moderate to high degrees of target category membership (.40 ≤ s ≤ .80). Within each time constraint condition, there were differences in response criteria as a function of signal ambiguity. Participants in the local condition had more liberal response criteria compared to participants in the global condition.

There was no significant effect of self-terminated search duration on sensitivity or response criteria. To examine the effect of participant control over search duration, participants in the global time constraint condition with average search durations of 3500-4500 ms were selected for comparison to participants in the local 4000 ms fixed-interval time constraint condition. There were significant differences in sensitivities such that participants in the global time constraint condition with ∼4000 ms search durations had significantly higher sensitivities, indicating an effect of participant control over search duration. There were no significant differences in response criteria.

The current study investigated decision making elements that contribute to efficient and effective operator performance of information search and target detection. In addition to operator characteristics that impact performance outcomes, characteristics of the signal itself may also moderate signal detection.