The effects of increasing target prevalence on information processing during visual search

Abstract

The proportion of trials on which a target is presented (referred to as the target prevalence) during visual search influences the probability that the target will be detected. As prevalence increases, participants become biased toward reporting that the target is present. This bias results in an increase in detection rates for the target, coupled with an increased likelihood of making a false alarm. Previous work has demonstrated that, as prevalence increases, participants spend an increasing period of time searching on target-absent trials. The goal of the present study was to determine the information processing during the additional time spent searching on target-absent trials as prevalence increased. We recorded participants' eye movement behavior as they were engaged in low-prevalence (25% target-present trials), medium-prevalence (50%), or high-prevalence (75%) search. Increased prevalence primarily influenced search by increasing the time spent examining objects in the display, rather than by increasing the proportion of objects examined in each display. In addition, the additional time spent examining objects in high-prevalence target-absent trials was the result of revisiting objects. We discuss the implications of these results in relation to current models of search as well as ongoing efforts to alleviate the prevalence effect.

Failures of perception in the low-prevalence effect: Evidence from active and passive visual search.

“…Eye-tracking analyses showed that common targets were found more efficiently and identified more quickly than rare targets. Our findings strongly align with recent work by Godwin and colleagues (Godwin, Menneer, Cave, et al, 2015; Godwin, Menneer, Riggs, et al, 2015) and extend their work in two important ways. First, our RSVP experiments (Experiments 3 and 4) demonstrate that LPEs arise even when early search termination errors are not possible and when reflexive motor errors are extremely unlikely.…”

“…Once an observer has learned not to expect certain targets, it becomes more difficult for those targets to attract attention and more difficult for them to resonate with search intentions held in memory. Indeed, our findings are also in alignment with a more recent investigation by Godwin and colleagues (Godwin, Menneer, Riggs, et al, 2015; see also Godwin, Menneer, Cave, et al, 2015); their participants searched for two rotated T s (that differed considerably in color) among rotated L s (of assorted colors). As in our experiments, one target color was present in 45% of trials and its counterpart in 5% of trials.…”

The influence of experience upon information-sampling and decision-making behaviour during risk assessment in military personnel

“…This is very similar to the pattern of effects observed for the inexperienced participants, who spent longer searching and were more likely to respond 'haltpatrol' than the experienced participants. But the similarities go deeper still: in a previous study (Godwin et al, 2014), we also found that, when participants expected a target to be present, they made repeated visits to objects, just as the inexperienced participants did here with the PRIs.…”

“…However, in X-ray baggage screeners, there is a cost associated with this increase in accuracy: search is more accurate but less rapid for experienced searchers, who approach search in a consistently more cautious manner. This finding suggests that experienced X-ray baggage screeners may be more exhaustive in their searchers (Wolfe, Brunelli, Rubinstein, & Horowitz, 2013), perhaps due to spending longer examining each object or examining more objects (Godwin, Menneer, Cave, Thaibsyah, & Donnelly, 2014).…”

The Effect of Lifeguard Experience upon the Detection of Drowning Victims in a Realistic Dynamic Visual Search Task

“…The visual search tasks that are often used in the literature are, however, typically context-free searches for arbitrary features, such as black vertical and horizontal lines on a white background (Wolfe & Friedman-Hill, 1992). Even when experimenters use naturalistic stimuli, these are typically impoverished in order to maintain a high degree of experimental control (Godwin, Menneer, Cave, Thaibsyah, & Donnelly, 2015). This is further complicated by the dynamic stimuli used in this current study.…”