2013 Volume 32 Issue 1 Pages 40-48
In visual searches, target prevalence (the ratio of target-present to target-absent trials) affects miss rates. We are more likely to miss targets in situations in which targets rarely appear, such as during detection of dangerous materials by airport security or routine medical screening for breast and cervical cancer. This tendency is termed the "prevalence effect." Here, we review recent advances in visual search studies pertaining to this effect. First, we describe how target prevalence affects error rates, reaction time (RT), and criterion and sensitivity in target detection. Second, we discuss the mechanisms of the prevalence effect, especially response and motor errors, observers' conservative criterion shifts, and shortening of search termination times (RT for target-absent trials). Third, we discuss whether or not expectations regarding target prevalence influence search termination times and miss rates. Finally, based on previous studies we discuss how to prevent the prevalence effect in visual search.
