The face inversion effect in opponent-stimulus rivalry.

Malte Persike

doi:10.3389/fnhum.2014.00295

Abstract

The face inversion effect is regarded as a hallmark of face-specific processing, and can be observed in a large variety of visual tasks. Face inversion effects are also reported in binocular rivalry. However, it is unclear whether these effects are face-specific, and distinct from the general tendency of visual awareness to privilege upright objects. We studied continuous rivalry across more than 600 dominance epochs for each observer, having faces and houses rival against their inverted counterparts, and letting faces rival against houses in both upright and inverted orientation. We found strong inversion effects for faces and houses in both the frequency of dominance epochs and their duration. Inversion effects for faces, however, were substantially larger, reaching a 70:30 distribution of dominance times for upright versus inverted faces, while a 60:40 distribution was obtained for upright versus inverted houses. Inversion effects for faces reached a Cohen's d of 0.85, compared to a value of 0.33 for houses. Dominance times for rivalry of faces against houses had a 60:40 distribution in favor of faces, independent of the orientation of the objects. These results confirm the general tendency of visual awareness to prefer upright objects, and demonstrate the outstanding role of faces. Since effect size measures clearly distinguish face stimuli in opponent-stimulus rivalry, the method is highly recommended for testing the effects of face manipulations against non-face reference objects.

Highlights

When presenting highly dissimilar images to corresponding regions of either eye an observer experiences binocular rivalry— dynamic alternations of two percepts that compete for dominance
While in earlier conceptualizations it was proposed that binocular rivalry reflected competition between monocular neurons within the LGN and the primary visual cortex (Blake, 1989), it has since been established that competitive interactions at multiple neural sites are involved, including lower and eye-specific, and higher cortical areas which respond to input from both eyes (Blake and Logothetis, 2002; Tong et al, 2006)
Using dichoptic presentation of face and house stimuli it was found that activation in the face-tuned fusiform face area (FFA; Kanwisher and Yovel, 2006) alternated with activation in the parahippocampal place area (PPA), which preferably responds to houses and places (Tong et al, 1998), in the same way as if the two single eyes were stimulated with faces and houses in physical alternation

Summary

Introduction

When presenting highly dissimilar images to corresponding regions of either eye an observer experiences binocular rivalry— dynamic alternations of two percepts that compete for dominance. Exploring the remainder FFA activity during the epochs where the perception of intact face stimuli was suppressed it was found that this activity was still greater than the activity caused by invisible scrambled faces (Jiang and He, 2006). This suggests that stimulus processing still reaches higher level areas even if conscious perception is suppressed (Tong et al, 2006)

Methods

Results

Conclusion