Upright or inverted, entire or exploded: right-hemispheric superiority in face recognition withstands multiple spatial manipulations.

Giulia Prete,Luca Tommasi,Daniele Marzoli

doi:10.7717/peerj.1456

Abstract

Background. The ability to identify faces has been interpreted as a cerebral specialization based on the evolutionary importance of these social stimuli, and a number of studies have shown that this function is mainly lateralized in the right hemisphere. The aim of this study was to assess the right-hemispheric specialization in face recognition in unfamiliar circumstances.Methods. Using a divided visual field paradigm, we investigated hemispheric asymmetries in the matching of two subsequent faces, using two types of transformation hindering identity recognition, namely upside-down rotation and spatial “explosion” (female and male faces were fractured into parts so that their mutual spatial relations were left intact), as well as their combination.Results. We confirmed the right-hemispheric superiority in face processing. Moreover, we found a decrease of the identity recognition for more extreme “levels of explosion” and for faces presented upside-down (either as sample or target stimuli) than for faces presented upright, as well as an advantage in the matching of female compared to male faces.Discussion. We conclude that the right-hemispheric superiority for face processing is not an epiphenomenon of our expertise, because we are not often exposed to inverted and “exploded” faces, but rather a robust hemispheric lateralization. We speculate that these results could be attributable to the prevalence of right-handedness in humans and/or to early biases in social interactions.

Highlights

The ability to recognize conspecifics is crucial for survival, and it has been demonstrated in a variety of species that visual cues are very important to this purpose, especially for social animals (i.e., Gronenberg, Ash & Tibbetts, 2007; Parr, 2011; Dahl et al, 2013; Somppi et al, 2014)
A number of studies have shown that the fusiform gyrus, in the right hemisphere, is the brain area involved in face processing (Gross, Rocha-Miranda & Bender, 1972; Bruce, Desimone & Gross, 1981; McCarthy et al, 1997), so that this area has been named “fusiform face area” (Kanwisher, McDermott & Chun, 1997; Kanwisher & Yovel, 2006)
The effect of the visual field was highly significant, showing that the identity of two faces was better matched when target stimuli were presented in the left visual field than in the right visual field

Summary

Introduction

The ability to recognize conspecifics is crucial for survival, and it has been demonstrated in a variety of species that visual cues are very important to this purpose, especially for social animals (i.e., Gronenberg, Ash & Tibbetts, 2007; Parr, 2011; Dahl et al, 2013; Somppi et al, 2014). The ability to identify faces has been interpreted as a cerebral specialization based on the evolutionary importance of these social stimuli, and a number of studies have shown that this function is mainly lateralized in the right hemisphere. We conclude that the right-hemispheric superiority for face processing is not an epiphenomenon of our expertise, because we are not often exposed to inverted and “exploded” faces, but rather a robust hemispheric lateralization. We speculate that these results could be attributable to the prevalence of right-handedness in humans and/or to early biases in social interactions

Objectives

Methods

Results

Conclusion