Configural superiority for varying contrast levels

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.

Gestalts at threshold could reveal Gestalts as predictions

“…Another key goal we had was to properly assess how contrast and saliency manipulations could help us understand the processing of configural Gestalts and potentially unveil a differential role of predictive processing for these stimuli (one of the main goals of the current paper). We agreed that these two goals would not coexist well in one single paper (given the focus on replication and extension of the claims by Bratch et al 78 , in Moors et al 77 ) and that a separate analysis of the relevant parts of the data, combined with new experiments was the best way forward to achieve the second goal. We now analyzed the data to include only the conditions with the same number of elements and similar spatial frequency content (excluding some conditions that were relevant only for a comparison with the work of Bratch et al and not relevant to address our current questions).…”

“…Upon the conception of the study that would lead to the present manuscript and the previously mentioned one, the authors had two goals. One of these was to replicate and extend the study by Bratch et al 78 , looking at clarifying the claims of less efficient information processing and higher thresholds for CSE-inducing stimuli when compared to their constituent parts (a claim that is in conflict with the previous literature on the matter, see 77 ). Another key goal we had was to properly assess how contrast and saliency manipulations could help us understand the processing of configural Gestalts and potentially unveil a differential role of predictive processing for these stimuli (one of the main goals of the current paper).…”

“…Experiment 1 consists of the reanalysis of data from two experiments recently reported elsewhere by the authors 77 . Upon the conception of the study that would lead to the present manuscript and the previously mentioned one, the authors had two goals.…”

“…We also adopted a simpler modeling of the data to assess at which data point (from a sample of actually recorded data points) discrimination the Gestalt conditions differed from the control conditions and how that relates to the threshold. We refer to Moors et al 77 , for more detailed information.…”

“…In this example, contrast increases from the leftmost to the rightmost display. Adapted from Moors et al 77 . …”