Gestalt Perceptual Organization of Visual Stimuli Captures Attention Automatically: Electrophysiological Evidence

Francesco Marini,Carlo A Marzi

doi:10.3389/fnhum.2016.00446

Abstract

The visual system leverages organizational regularities of perceptual elements to create meaningful representations of the world. One clear example of such function, which has been formalized in the Gestalt psychology principles, is the perceptual grouping of simple visual elements (e.g., lines and arcs) into unitary objects (e.g., forms and shapes). The present study sought to characterize automatic attentional capture and related cognitive processing of Gestalt-like visual stimuli at the psychophysiological level by using event-related potentials (ERPs). We measured ERPs during a simple visual reaction time task with bilateral presentations of physically matched elements with or without a Gestalt organization. Results showed that Gestalt (vs. non-Gestalt) stimuli are characterized by a larger N2pc together with enhanced ERP amplitudes of non-lateralized components (N1, N2, P3) starting around 150 ms post-stimulus onset. Thus, we conclude that Gestalt stimuli capture attention automatically and entail characteristic psychophysiological signatures at both early and late processing stages.HighlightsWe studied the neural signatures of the automatic processes of visual attention elicited by Gestalt stimuli. We found that a reliable early correlate of attentional capture turned out to be the N2pc component. Perceptual and cognitive processing of Gestalt stimuli is associated with larger N1, N2, and P3

Highlights

The human brain makes sense of the multitude of sensory stimuli in the environment by grouping them into meaningful representations such as forms or objects
Because the N2pc is a contralateral minus ipsilateral difference wave with a PO distribution, this finding indicates that Gestalt configurations elicited enhanced N2 amplitudes when presented in either hemifield simultaneously with a non-Gestalt stimulus in the opposite hemifield
We provided electrophysiological evidence supporting the notion that the human brain differentiates responses to visual stimuli with Gestalt configurations from physically matched stimuli without Gestalt configurations starting at about 150 ms post-stimulus

Summary

Introduction

The human brain makes sense of the multitude of sensory stimuli in the environment by grouping them into meaningful representations such as forms or objects. Because we were interested in truly automatic processes, we used a simple detection task in which participants were required to detect the onset of any visual stimulus and respond as quickly as possibly by pressing a key without having to discriminate the stimuli or to make a choice. We adopted this simple detection task in order to avoid any top-down attentional bias, such as those due to target-template matching. This aspect represents a substantial difference relative to typical visual search tasks (pop-out or conjunction) and ensures that any attentional capture reflects genuinely automatic processes

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