The guidance of visual search by shape features and shape configurations.

Abstract

Representations of target features (attentional templates) guide attentional object selection during visual search. In many search tasks, targets objects are defined not by a single feature but by the spatial configuration of their component shapes. We used electrophysiological markers of attentional selection processes to determine whether the guidance of shape configuration search is entirely part-based or sensitive to the spatial relationship between shape features. Participants searched for targets defined by the spatial arrangement of two shape components (e.g., hourglass above circle). N2pc components were triggered not only by targets but also by partially matching distractors with one target shape (e.g., hourglass above hexagon) and by distractors that contained both target shapes in the reverse arrangement (e.g., circle above hourglass), in line with part-based attentional control. Target N2pc components were delayed when a reverse distractor was present on the opposite side of the same display, suggesting that early shape-specific attentional guidance processes could not distinguish between targets and reverse distractors. The control of attention then became sensitive to spatial configuration, which resulted in a stronger attentional bias for target objects relative to reverse and partially matching distractors. Results demonstrate that search for target objects defined by the spatial arrangement of their component shapes is initially controlled in a feature-based fashion but can later be guided by templates for spatial configurations. (PsycINFO Database Record

Simple shapes guide visual attention based on their global outline or global orientation contingent on search goals.

“…In contrast, the 150-ms interval between cue and target was at least sufficient to ignore the nonmatching but salient shape singletons entirely. This result appears to be in line with earlier claims of attentional capture by target-matching shapes (e.g., Adamo et al, 2010; Berggren & Eimer, 2018; Biderman et al, 2017; Lien et al, 2010; McCants et al, 2018).…”

“…Therefore, the guiding feature(s) might have been all, some, or one of the target-matching edges of the shape instead of the global shape outline (cf. McCants et al, 2018). To test whether attentional guidance during search for shapes in general and in Experiment 1, in particular, was based on exactly matching edges, we used a cue shape with reconfigured edges in Experiment 2.…”

“…Adamo et al (2010) showed parallel attentional control settings for shape and location. Finally, Berggren and Eimer (2018) found neurophysiological evidence for shape-specific attentional capture (see also, McCants et al, 2018). However, in all these studies, edge orientations of the matching cue and the target were at least partly the same, leaving it open if participants can efficiently search for a global shape outline consisting of a combination of oriented edges.…”

Object-based target templates guide attention during visual search.

“…Desired sample size was a priori defined at 12 participants, consistent with many previous N2pc and SPCN studies in our lab and elsewhere (e.g., Berggren & Eimer, 2016a; Luck & Hillyard, 1994). To assess the sufficiency of this sample size, we assessed the effect size from two previous studies from our group that were conceptually closest to the current study, which examined differences in N2pc response to targets defined by a configuration of two features (i.e., vs. objects containing relevant features but task-irrelevant due to their specific configuration; Berggren & Eimer, 2016b, Experiment 3; McCants, Berggren, & Eimer, in press, Experiments 1 and 2). Across these experiments, effect sizes (based on Cohen’s d ; mean difference divided by pooled standard deviation method) for differences in N2pc mean amplitudes for a target alone relative to a target in competition with a nontarget in an incorrect configuration were used as the basis for power analyses, where power of 0.8 and an alpha level of 0.05 was assumed.…”

The capacity of multiple-target search

“…Therefore, for the sake of external validity it is mandatory to investigate to what extent the findings generalize to more complex stimuli. So far, existing research on that topic has led to mixed findings (Andersen et al, 2015;Bahle et al, 2019;Biderman et al, 2017;McCants et al, 2018;Ort et al, 2018;Wolfe et al, 1990). .…”