Configural superiority for varying contrast levels
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Configural superiority for varying contrast levels Pieter Moors 1 & Thiago Leiros Costa 1 & Johan Wagemans 1
# The Psychonomic Society, Inc. 2019
Abstract Observers can search for a target stimulus at a particular speed and accuracy. Adding an identical context to each stimulus can improve performance when the resulting stimuli form clearly discriminable configurations. This search advantage is known as the configural superiority effect (CSE). A recent study showed that embedding these stimuli in noise revealed lower contrast thresholds for part-stimuli compared to configural stimuli (Bratch et al., Journal of Experimental Psychology. Human Perception and Performance, 42(9), 1388–1398, 2016). This contrasts with the accuracy advantages traditionally associated with CSEs. In this study, we aimed to replicate the results of Bratch et al. and asked whether the benefit for part-stimuli held across the full psychometric function. Additionally, we tested whether embedding the stimuli in noise was crucial for obtaining their result and whether different contrast definitions affected the results. Furthermore, we used control stimuli that were more directly comparable. Our results showed a detection benefit for the Gestalt context stimuli in all conditions. Together, these results are in line with the literature on CSEs and do not seem to support the recent claim that Gestalts are processed less efficiently than part stimuli. Inspired by this, we sketch how contrast manipulations could be an additional tool to study how Gestalts are processed. Keywords Perceptual organization . Visual perception . Visual search
Introduction Configural Gestalts are characterized by part-whole relationships (i.e., stimuli that are qualitatively different from the sum of their parts) and are central to human visual perception. The study of these phenomena (or, perceptual organization more broadly) has frequently relied on phenomenology alone through showcasing the effects (reviewed by Wagemans et al., 2012 and Wagemans, 2018). In the 1970s the information processing literature offered a few examples of quantification of these phenomena (Kolers & Pomerantz, 1971; Pomerantz & Garner, 1973). However, more sophisticated psychophysical approaches remained absent for a long time. In the 1990s, this started to change with the quantitative study of grouping by proximity (Kubovy & Wagemans, 1995) and contour integration (Field, Hayes, & Hess, 1993; Kovacs & Julesz, 1993). As a result, psychophysical methods are now Pieter Moors and Thiago Leiros Costa contributed equally to this work. * Pieter Moors [email protected] 1
Laboratory of Experimental Psychology, Department of Brain and Cognition, KU Leuven, Tiensestraat 102 - box 3711, BE-3000 Leuven, Belgium
part of the standard approach to study mid-level vision (e.g. (Claessens & Wagemans, 2008; Machilsen, Pauwels, & Wagemans, 2009; Machilsen & Wagemans, 2011; Panis, De Winter, Vandekerckhove, & Wagemans, 2008; Poljac, de-Wit, & Wagemans, 2012). The main conclusion from this literature seems
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