Signs of predictive coding in dynamic facial expression processing

J W Schultz1, H Bülthoff2, K Kaulard2

1Department of Psychology, Durham University, United Kingdom
2Department Perception, Cognition and Action, Max Planck Institute Biological Cybernetics, Germany

Contact: j.w.r.schultz@durham.ac.uk

Processing social information contained in facial motion is likely to involve neural mechanisms in hierarchically organized brain regions. To investigate processing of facial expressions, we acquired functional magnetic imaging data from 11 participants observing videos of 12 facial expressions. Stimuli were presented upright (clearly perceivable social information) and upside-down (disrupted social information). We assessed the amount of information contained in the brain activation patterns evoked by these expressions with multivariate searchlight analyses. We found reliable above-chance decoding performance for upright stimuli only in the left superior temporal sulcus region (STS) and for inverted stimuli only in the early visual cortex (group effects, corrected for family-wise errors resulting from multiple comparisons across gray matter voxels). Predictive coding proposes that inferences from high-level areas are subtracted from incoming sensory information in lower-level areas through feedback. Accordingly, we propose that upright stimuli activate representations of facial expressions in STS, which induces feedback to early visual areas and reduced processing in those regions. In contrast, we propose that upside-down stimuli fail to activate representations in STS and thus are processed longer in early visual cortex. Predictive coding might prove a useful framework for studying the network of brain regions processing social information.

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