Abstract
Perceptual grouping has been implicated as a mechanism for the holistic perception of faces. Using the composite task, Curby et al. (2013) found that holistic processing of faces, but not objects, is reduced when the backgrounds are misaligned and different colors. One implication of this study is that background color differences are enough to disrupt holistic processing of faces, but background color consistency is not enough to induce holistic processing for objects. Nonetheless, observers do sometimes show holistic processing of novice object categories (e.g., Greebles interleaved with faces). Recently, Bukach et al. (2015) found that novices processed birds holistically, but this novice holistic processing was negatively correlated with species matching ability. Here, we investigated whether novice holistic processing is influenced by perceptual grouping cues. Fifteen novices completed a bird composite task in which bird heads and bodies were always aligned, but background colors were either grouped (uniform color/aligned) or ungrouped (different colors/misaligned). Participants decided whether the cued part of sequentially presented bird composites were same or different, while attempting to ignore both the non-cued part and background changes. There was a significant interaction between congruency and grouping (p = .045). Surprisingly, the congruency effect was larger for ungrouped than grouped trials (Δd' = .805 vs. .456 respectively), opposite of the holistic processing pattern. This effect was driven solely by reduced accuracy for nonmatching congruent trials with a uniform aligned background. We speculate that whereas processing during incongruent trials was focused primarily on resolving the ambiguity of the target response, processing during congruent trials allowed more processing of background cues. The slower response times of non-matching trials suggest they may have been particularly vulnerable due to the need for more evidence or lack of confidence in the response. Perceptual grouping cues may compete with target responses in the composite paradigm.
Meeting abstract presented at VSS 2017