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Disrupting perceptual grouping of face parts impairs holistic face processing.

Curby KM, Goldstein RR, Blacker K - Atten Percept Psychophys (2013)

Bottom Line: Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1).This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3).These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Faculty of Human Sciences, Macquarie University, Sydney, New South Wales, Australia. kim.curby@mq.edu.au

ABSTRACT
Face perception is widely believed to involve integration of facial features into a holistic perceptual unit, but the mechanisms underlying this integration are relatively unknown. We examined whether perceptual grouping cues influence a classic marker of holistic face perception, the "composite-face effect." Participants made same-different judgments about a cued part of sequentially presented chimeric faces, and holistic processing was indexed as the degree to which the task-irrelevant face halves impacted performance. Grouping was encouraged or discouraged by adjusting the backgrounds behind the face halves: Although the face halves were always aligned, their respective backgrounds could be misaligned and of different colors. Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1). This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3). These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.

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Related in: MedlinePlus

Trial structure used in Experiment 1, with examples from trials in which the context (left) encouraged or (right) discouraged the perceptual grouping of the face parts (referred to as the grouped and ungrouped conditions, respectively). The dashed bracket served as the cue in each trial to indicate which part (top or bottom) the participant should make the matching judgment on
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Fig2: Trial structure used in Experiment 1, with examples from trials in which the context (left) encouraged or (right) discouraged the perceptual grouping of the face parts (referred to as the grouped and ungrouped conditions, respectively). The dashed bracket served as the cue in each trial to indicate which part (top or bottom) the participant should make the matching judgment on

Mentions: Participants performed a part (top or bottom) matching task with chimeric images made from the tops and bottoms of different stimuli. Depending on which of two conditions the participants were randomly assigned to, they made such judgments about either face or car stimuli. The two image parts were separated by a black line six pixels wide. Each trial proceeded as follows: fixation screen (1,000 ms), a chimeric stimulus (1,000 ms), a pattern mask (2,000 ms), and a second chimeric stimulus (2,500 ms or until response). In “grouped” trials, the backgrounds of the top and bottom images were aligned and their colors matched. In “ungrouped” trials, the backgrounds of the top and bottom images were misaligned and of different colors (see Fig. 2). A cue, in the form of a horizontal bracket, appeared above or below the second chimeric image to indicate which of the two halves, top or bottom, the participants should judge to be the “same” or “different” in the two chimeric images. On half of the trials, the relationship between the task-irrelevant parts was congruent with that of the task-relevant parts, and on the other half the relationships were incongruent. For example, on a “congruent” bottom-matching trial, if the bottom parts of the two chimeric images were the same, the top parts would also match. In an “incongruent” trial, if the bottoms of the two images matched, the tops would differ (and vice versa). To the degree that participants were able to base their judgments on only the task-relevant part, without interference from the task-irrelevant part, there should be no effect of congruency. In previous studies, the difference in performance between congruent and incongruent trials has been greater for upright faces than for either inverted faces or nonface objects (Curby, Johnson, & Tyson, 2012; Gauthier, Curran, Curby, & Collins, 2003; Richler, Tanaka, Brown, & Gauthier, 2008). Notably, the degree to which the congruency effect was modulated by the physical misalignment of the face parts (i.e., the interaction between the effect of congruency and part misalignment) has also separated the performance between face and nonface (or inverted face) conditions in this task and is an established index of holistic processing (e.g., Richler, Cheung, et al. 2011). Trials in our study were blocked by background types (aligned/same color vs. misaligned/different colors), and four blocks of 32 trials were performed for each background type in a random order. Participants were given a practice session consisting of 16 trials to ensure that they were familiar with the task format. Trials in which a participant failed to input a response were excluded from the analysis. Furthermore, the data from four participants who failed to respond to at least 85 % of the trials were excluded (the remaining participants lost an average of < 3 % of trials). In addition, the data from six participants were excluded due to poor performance (i.e., d′ ≤ 0 in at least one condition).Fig. 2


Disrupting perceptual grouping of face parts impairs holistic face processing.

Curby KM, Goldstein RR, Blacker K - Atten Percept Psychophys (2013)

Trial structure used in Experiment 1, with examples from trials in which the context (left) encouraged or (right) discouraged the perceptual grouping of the face parts (referred to as the grouped and ungrouped conditions, respectively). The dashed bracket served as the cue in each trial to indicate which part (top or bottom) the participant should make the matching judgment on
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3824569&req=5

Fig2: Trial structure used in Experiment 1, with examples from trials in which the context (left) encouraged or (right) discouraged the perceptual grouping of the face parts (referred to as the grouped and ungrouped conditions, respectively). The dashed bracket served as the cue in each trial to indicate which part (top or bottom) the participant should make the matching judgment on
Mentions: Participants performed a part (top or bottom) matching task with chimeric images made from the tops and bottoms of different stimuli. Depending on which of two conditions the participants were randomly assigned to, they made such judgments about either face or car stimuli. The two image parts were separated by a black line six pixels wide. Each trial proceeded as follows: fixation screen (1,000 ms), a chimeric stimulus (1,000 ms), a pattern mask (2,000 ms), and a second chimeric stimulus (2,500 ms or until response). In “grouped” trials, the backgrounds of the top and bottom images were aligned and their colors matched. In “ungrouped” trials, the backgrounds of the top and bottom images were misaligned and of different colors (see Fig. 2). A cue, in the form of a horizontal bracket, appeared above or below the second chimeric image to indicate which of the two halves, top or bottom, the participants should judge to be the “same” or “different” in the two chimeric images. On half of the trials, the relationship between the task-irrelevant parts was congruent with that of the task-relevant parts, and on the other half the relationships were incongruent. For example, on a “congruent” bottom-matching trial, if the bottom parts of the two chimeric images were the same, the top parts would also match. In an “incongruent” trial, if the bottoms of the two images matched, the tops would differ (and vice versa). To the degree that participants were able to base their judgments on only the task-relevant part, without interference from the task-irrelevant part, there should be no effect of congruency. In previous studies, the difference in performance between congruent and incongruent trials has been greater for upright faces than for either inverted faces or nonface objects (Curby, Johnson, & Tyson, 2012; Gauthier, Curran, Curby, & Collins, 2003; Richler, Tanaka, Brown, & Gauthier, 2008). Notably, the degree to which the congruency effect was modulated by the physical misalignment of the face parts (i.e., the interaction between the effect of congruency and part misalignment) has also separated the performance between face and nonface (or inverted face) conditions in this task and is an established index of holistic processing (e.g., Richler, Cheung, et al. 2011). Trials in our study were blocked by background types (aligned/same color vs. misaligned/different colors), and four blocks of 32 trials were performed for each background type in a random order. Participants were given a practice session consisting of 16 trials to ensure that they were familiar with the task format. Trials in which a participant failed to input a response were excluded from the analysis. Furthermore, the data from four participants who failed to respond to at least 85 % of the trials were excluded (the remaining participants lost an average of < 3 % of trials). In addition, the data from six participants were excluded due to poor performance (i.e., d′ ≤ 0 in at least one condition).Fig. 2

Bottom Line: Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1).This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3).These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Faculty of Human Sciences, Macquarie University, Sydney, New South Wales, Australia. kim.curby@mq.edu.au

ABSTRACT
Face perception is widely believed to involve integration of facial features into a holistic perceptual unit, but the mechanisms underlying this integration are relatively unknown. We examined whether perceptual grouping cues influence a classic marker of holistic face perception, the "composite-face effect." Participants made same-different judgments about a cued part of sequentially presented chimeric faces, and holistic processing was indexed as the degree to which the task-irrelevant face halves impacted performance. Grouping was encouraged or discouraged by adjusting the backgrounds behind the face halves: Although the face halves were always aligned, their respective backgrounds could be misaligned and of different colors. Holistic processing of face, but not of nonface, stimuli was significantly reduced when the backgrounds were misaligned and of different colors, cues that discouraged grouping of the face halves into a cohesive unit (Exp. 1). This effect was sensitive to stimulus orientation at short (200 ms) but not at long (2,500 ms) encoding durations, consistent with the previously documented temporal properties of the holistic processing of upright and inverted faces (Exps. 2 and 3). These results suggest that grouping mechanisms, typically involved in the perception of objecthood more generally, might contribute in important ways to the holistic perception of faces.

Show MeSH
Related in: MedlinePlus