Asymmetry of perception in free viewing of chimeric faces

Configurational coding, familiarity and the right hemisphere advantage for face recognition in sheep

“…Similar results are found for children [4,40] and commisurotomy patients [22,33]. The left visual hemi®eld (LVF) also plays a disproportionate role in judgements of a ective state with chimeric faces, where half of the face is smiling and half is frowning [20,21]. It is thought that this asymmetry in perception arises from the neural lateralisation which has been reported by various human brain imaging studies such as Positron Emission Topography (PET) [34], functional Magnetic Resonance Imaging (fMRI) [16,29] and Magneto-Encephalography (MEG) [35] in normal subjects, and by lesion localisation in prosopagnosic patients [7 for review].…”

“…Similar to those used by Overman and Doty [25]; . Hemi®eld chimeric Ð The traditional chimeric face stimuli [21,24] where the left and right of two separate faces (in this case the rewarded and nonrewarded) are combined to form one.…”

“…Another method has used split brain macaques where presentations can be made purely to one brain hemisphere, and this did yield an LVF advantage [14] although previous attempts to do so by the same group had failed [12,13]. Finally, Morris and Hopkins [24] found a bias in two out of three chimps (pan troglodytes) from the Savage±Rumbaugh project, performing Levy's [21] happy/sad discrimination on chimeric faces. This appears to be the strongest evidence to date for such perceptual asymmetry in a non-human species.…”

Asymmetries of the human social brain in the visual, auditory and chemical modalities

“…The amount of literature is more than abundant on this aspect and two main models have been proposed to explain emotional lateralization (see Demaree et al (2005) for a comprehensive review). The right hemisphere hypothesis posits a right-hemispheric superiority in production and perception of all emotional expressions (Campbell 1978;Ley & Bryden 1979;Levy et al 1983;Tucker et al 1995), whereas the valence hypothesis assumes a left-hemispheric superiority for the processing of positive emotions and a righthemispheric superiority for the processing of negative emotions (Reuter-Lorenz & Davidson 1981;Borod et al 1997). The latter model is also in line with another influential model of hemispheric lateralization, the 'approach-withdrawal' model, positing that from the standpoint of motivation, the left hemisphere would be more strongly associated with approaching rewards and the right hemisphere to withdrawing from punishments (Davidson 1993).…”

Laterality Biases to Chimeric Faces in Asperger Syndrome: What is Right About Face-Processing?

“…Davidson, Mednick, Mass, Saron and Schaffer (1987) replicated and extended this finding, and suggested that such a pattern is inconsistent with the notion that the right hemisphere alone is involved in processing all emotions. Using chimeric faces and a free-viewing administration, Levy, Heller, Banich and Burton (1983) showed that right-handed subjects judged faces as happier when the smile was on the left side of the face (with neutral on the right), when compared with the converse. Replications and extensions of these findings were reported in subsequent studies (Hoptman & Levy, 1988;Luh, Ruekert & Levy, 1991).…”