Integrating expected search time and target detection probability in visual search strategies: The undervaluing of search time

In trouble-shooting, subjects choose the order in which they test hypotheses. This choice often involves a trade-off between the time it takes to test a hypothesis and the probability that the hypothesis is correct. In visual search, subjects may have to choose which of two displays they are going to search first. The trade-off is similar in that the display most likely to contain the target may take longer to search. A series of experiments investigated whether subjects are efficient in the way they trade-off the size of a visual display and the probability it contains the target. Subjects were presented with information about the size of each of two displays and their respective probabilities of containing the target. The task was to choose which display to search first and then conduct the search as rapidly as possible. The first experiment showed that subjects did follow specific patterns of display choice, and that subjects have a strong tendency to overweigh probability information. Experiment 1 also showed that subjects generally fail to take into consideration the effect of highlighting the target. When a target is highlighted, the size of the display has a negligible effect on search time and therefore should make the size of the display unimportant in choosing which display to search. The display choice of most subjects was uninfluenced by target highlighting. Experiment 2 used a wider range of display sizes to see if that would make display size more salient and possibly induce subjects to pay more attention to it. As in Experiment 1, subjects paid too much attention to the probability that a display contains the target and not enough attention to the time it takes to search the display. Three methods of training subjects to consider the time to test a hypothesis when choosing hypotheses were evaluated in Experiment 4. Even though the surface characteristics of the training materials and the visual search task differed, training did improve subjects' performance on the visual search task. The relative neglect of the time it takes to test hypotheses may be a general phenomenon