Understanding the contribution of target repetition and target expectation to the emergence of the prevalence effect in visual search

Abstract

Behavior in visual search tasks is influenced by the proportion of trials on which a target is presented (the target prevalence). Previous research has shown that when target prevalence is low (2 % prevalence), participants tend to miss targets, as compared with higher prevalence levels (e.g., 50 % prevalence). There is an ongoing debate regarding the relative contributions of target repetition and the expectation that a target will occur in the emergence of prevalence effects. In order to disentangle these two factors, we went beyond previous studies by directly manipulating participants’ expectations regarding how likely a target was to appear on a given trial. This we achieved without using cues or feedback. Our results indicated that both target repetition and target expectation contribute to the emergence of the prevalence effect.Electronic supplementary materialThe online version of this article (doi:10.3758/s13423-015-0970-9) contains supplementary material, which is available to authorized users.

Hybrid foraging search: Searching for multiple instances of multiple types of target

“…This has been seen in blue jays who will pass over less common prey while foraging for the more common (Bond & Kamil, 2002). Similar effects are seen in search when one target type is rarer than another (Godwin et al, 2015; Hout, Walenchok, Goldinger, & Wolfe, 2015). …”

Modeling Lag‐2 Revisits to Understand Trade‐Offs in Mixed Control of Fixation Termination During Visual Search

“…Second, our results can also help to offer new insights into how participants fail to detect targets in visual search. It has been noted that targets are often missed as a consequence of failures of perceptual identification (Cain et al., ; Schwark et al., )—that is, even after fixating the target object, the target is still missed by participants (Engel, ; Godwin et al., ,a,b; Godwin et al., ; Gould & Cairn, ; Hooge & Erkelens, ; Hout, Walenchok, Goldinger, & Wolfe, ; Nodine & Kundel, ). These failures have important societal consequences, such as in radiographic image screening, where tumors can go undetected and missed by searchers.…”

“…The existence of perceptual identification errors has been used as evidence against strict direct‐control accounts, with such occurrences being regarded as a natural by‐product of the fact that fixations can be terminated by an indirect mechanism (e.g., an autonomous timer) that drives fixations to new locations irrespective of whether or not the processing of an object at a given fixation location has been completed. However, more recent studies (Godwin, Menneer, Riggs, Cave, & Donnelly, ; Godwin et al., ; Hout et al., ) have found that perceptual identification errors are more likely to occur when the target is presented on a small proportion of trials (5% of trials) compared with a higher proportion of trials (45%), perhaps because of priming from target repetition and/or expectations about the likelihood of a target being presented (Godwin et al., ,b). This finding suggests that failures to detect the target upon fixating it may reflect object identification failures rather than being a consequence of some indirect mechanism, as predicted by indirect‐control accounts.…”

“…Importantly, we wanted to test whether a global parameter was required to simulate the fixation behavior, and if so, what form this parameter takes. That is, if lag‐2 revisits are a form of trade‐off between the overall rate of search and the accuracy in target detection on the first fixation, then participants should be less likely to make lag‐2 revisits when the objects being fixated are more likely to be a target (Godwin et al., ,b; Hout et al., in press). If so, then this would provide evidence of a new, previously unknown global parameter (the value of which is affected by the probability of any fixated object being the target) influencing the push‐pull relationship between online cognitive processing and the drive to program and initiate new saccades in order to proceed with search.…”

Using Eye Movements to Understand how Security Screeners Search for Threats in X-Ray Baggage

“…For example, a reduction in target prevalence increases failures of perceptual selection, whereby searchers fixate fewer objects in each trial as prevalence is reduced [48]. It is worth noting that efforts to overcome this shortcoming by providing feedback in relation to where fixations have and have not been made are unlikely to help [49,50].…”