"Satisfaction" in search: Individuals' own search expectations predict their errors in multiple-target search.

When people search for multiple targets in a display, finding one target hinders their ability to find additional targets. These errors were originally proposed to stem from a "satisfaction" with finding a first target that leads people to prematurely stop searching. However, empirical evidence for this premise has been elusive, prompting consideration of other theories. We returned to the satisfaction proposal and assessed whether people generate expectations regarding the likelihood of multiple targets that lead to search biases that, in turn, predict the rates at which additional targets are missed. Participants searched for one or two targets among distractors. To measure accuracy, most trials allowed search to progress to completion. The remaining trials terminated when participants had found their first target. In these cases, participants guessed whether an additional (unfound) target was present. The time needed to find a first target was inversely related to the searchers' expectations that a second target would be present. These expectations underestimated objective reality, and the strength of an individual's one-target bias was directly related to his or her likelihood of missing subsequent targets. Thus, people's expectations-based on their own behavior-likely impacted search performance, providing a novel mechanistic explanation for the previously posited "satisfaction-of-search" errors.