Dwelling, rescanning, and skipping of distractors explain search efficiency in difficult search better than guidance by the target

Abstract

Prominent models of overt and covert visual search focus on explaining search efficiency by visual guidance. That some searches are fast whereas others are slow is explained by the ability of the target to guide attention to the target's position. Comparably little attention is given to other variables that might also influence search efficiency, such as dwelling on distractors, skipping distractors, and revisiting distractors. Here, we examine the relative contributions of dwelling, skipping, rescanning, and the use of visual guidance, in explaining visual search times in general, and the similarity effect in particular. The hallmark of the similarity effect is more efficient search for a target that is dissimilar to the distractors compared to a target that is similar to the distractors. In the present experiment, participants have to find an emotional face target among nine neutral face non-targets. In different blocks, the target is either more or less similar to the non-targets. Eye-tracking is used to separately measure selection latency, dwelling on distractors, and skipping and revisiting of distractors. As expected, visual search times show a large similarity effect. Similarity also has strong effects on dwelling, skipping, and revisiting, but only weak effects on visual guidance. Regression analyses show that dwelling, skipping, and revisiting determine search times on trial level. The influence of dwelling and revisiting is stronger in target absent than in target present trials, whereas the opposite is true for skipping. The similarity effect is best explained by dwelling. Additionally, including a measure of guidance does not yield substantial benefits. In sum, results indicate that guidance by the target is not the sole principle behind fast search; rather, distractors are less often skipped, more often visited, and longer dwelled on in slow search conditions.

Dwelling on simple stimuli in visual search

“…Experiment 1 replicated previous findings (Horstmann, et al, 2016(Horstmann, et al, , 2017 and confirmed that in addition to skipping (the proportion of distractors that are excluded from inspection), dwelling (the time gaze is focused on a distractor) and revisiting (the frequency with which distractors are included for inspection repeatedly) were important predictors for search times. This is a notable finding because it shows that our previous observations are not limited to visual search for complex and naturalistic (face) stimuli.…”

“…3, top row. We do not present ANOVAs as we did in previous studies (e.g., Horstmann, Becker, & Ernst, 2017) because the central evidencethat is the effects of similarity on skipping, revisiting, and, in particular, dwellingis captured in the correlations between similarity on the one hand and skipping, revisiting, and dwelling on the other. Our main focus is on target-absent trials, because only in these trials can skipping, dwelling, and revisiting be observed independently of the processes that may lead to the selection of the target in target-present trials.…”

“…The first of such mechanisms that we consider here is the time spent checking candidate target items or dwell time. It has been acknowledged that irrespective of whether a single stimulus (Wolfe et al, 1989;Zelinsky, 2008) or groups of stimuli (Hulleman & Olivers, 2017) are attentionally investigated, the duration of this investigation process may be an effective cause rendering some searches inefficient, and that search is more efficient when only a short period of time is spent at the respective stimulus locations (e.g., Horstmann, Ansorge, & Scharlau, 2006;Horstmann, Herwig, & Becker, 2016;Horstmann, Becker, & Ernst, 2017;Wolfe, 2001;Wolfe & Horowitz, 2017). Correspondingly, search is less efficient if, for whatever reasons, attentional checking time is increased in a particular type of search.…”

“…However, there is still a lot of variation in search efficiency in highly inefficient search, when guidance is difficult or absent, indicating that dwelling and revisiting may be important variables to explain visual search efficiency. In a series of previous studies we have used eye tracking to measure dwell time and revisiting most directly Horstmann, Ernst, & Becker, 2019;Horstmann, Herwig, & Becker, 2016;Horstmann, Becker, & Ernst, 2017). Eye tracking was used to assess whether a distractor was looked at or not (skipping), and if so, for how long it was looked at during the first examination (dwelling) and whether the same distractor was looked at repeatedly (revisiting).…”

“…We focused on target-absent trials (cf. Horstmann et al, 2016Horstmann et al, , 2017 because they allow observations of distractor processing without interference from target-related processes. However, analyses for target-present trials are also reported for completeness.…”