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Brianna Sullivan, Michael Wenger, Rebecca Von Der Heide, Jennifer Bittner; The crowding effect and perceptual and decisional holism in the visual processing of faces. Journal of Vision 2008;8(6):888. doi: 10.1167/8.6.888.
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Two experiments examined the extent to which holism in visual perception can be revealed by way of the presence or absence of visual crowding. Martelli, Majaj, and Pelli (2005) used crowding—increases in threshold for contrast as a function of eccentricity—to propose an operational definition for holism: that holistic perception of an object is implicated if it can be identified when the entire object is presented within an isolation field (an area proportional to one-half eccentricity). This operational definition is considered from the perspective of general recognition theory (GRT, Ashby & Townsend, 1986), a theoretical rather than operational approach to defining holism. In this study, participants performed forced-choice identification tasks for two sets of face stimuli presented under conditions modeled on those used by Martelli and colleagues. In Experiment 1, participants identified one feature (the nose) presented alone or in a face context, and then three types of paired features in faces (the eyes and nose, eyes and mouth, or nose and mouth). In Experiment 2, participants performed the same identification tasks, but the stimuli were altered to increase critical spacing between the features, separating them into their own isolation fields. The experimental results replicated the threshold patterns documented by Martelli et al.: in Experiment 1, threshold data showed evidence for the benefit of a facial context in foveal presentation, and impairment in peripheral presentation, while in the Experiment 2 threshold data, both benefit and impairment were eliminated foveally and peripherally when critical spacing isolated the facial features. However, the GRT results from Experiments 1 and 2 revealed perceptual and especially decisional violations in both foveal and peripheral presentations, a disparity between current operational and theoretical definitions of holism which suggests that the crowding effect cannot serve to define holism in face perception.
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