Global interference during early visual processing: ERP evidence from a rapid global/local selective task

Virginie Beaucousin,Mathieu Cassotti,Olivier Houdé,Arlette Pineau,Nicolas Poirel,Grégory Simon

doi:10.3389/fpsyg.2013.00539

Abstract

Visual perception depends on the integration of local elements of a visual scene into a global frame. Evidence from behavioral studies shows that (1) the detection of the global frame is faster than the detection of the local parts, a phenomenon called the global advantage, and that (2) an interference of the global shape is also present during local processing. Together, these effects are called the global precedence effect (GPE). Even if the global advantage appears to impact neural processing as early as the first 100 ms post-stimulus, previous studies failed to find a global interference effect before 200 ms post-stimulus. Using for the first time a rapid display of letter component stimuli during a global/local selective task in which conditions with perceptual conflict, congruent and incongruent conditions were considered, the present event-related potential (ERP) study shows a global interference effect occurring as early as the time range of the N1 component. In particular, only congruent stimuli elicited similar N1 amplitude during the global and local tasks, whereas an increased of the N1 amplitude during the global task was observed (as compared to the local task) for both stimuli with perceptual conflict and incongruent stimuli. This finding corroborates the recent neural models of human visual perception.

Highlights

When we go for a walk in a forest, do we perceive the forest first or the trees? The investigation of the mechanism of global visual perception has benefitted from Navon’s work on global and local visual processing (Navon, 1977)
BEHAVIORAL RESULTS Participants were highly accurate in all experimental conditions
Interference effect was only present during local tasks: the congruent stimuli elicited faster response time (RT) than conflicting perceptual and incongruent stimuli (p < 0.001)

Summary

Introduction

The investigation of the mechanism of global visual perception has benefitted from Navon’s work on global and local visual processing (Navon, 1977). He designed an elegant, standard, paradigm using compound stimuli (for a review, see Navon, 2003). The presence of the non-target letter at the unattended global level slows down the detection of the target during local level processing (i.e., the global-to-local interference) Navon defined these effects as the “global precedence effect” (GPE) which was further illustrated by the famous statement that one sees “the forest before the trees” (Navon, 1977). The GPE can be reduced or even reversed by factors such as task variables (Shedden and Reid, 2001; Volberg and Hübner, 2007), the sparcity between the local features (Martin, 1979), the position of local elements and the saliency of the global form (Ripoll et al, 2005), the visual angle (Lamb and Robertson, 1990), the exposure duration (Andres and Fernandes, 2006) and the meaningfulness of the stimuli (Poirel et al, 2006, 2008), the dominance of global information is a robust effect (see Kimchi, 1992 and Hedgé, 2008, for a review)

Methods

Results

Conclusion