# Prediction error processing and sharpening of expected information across the face-processing hierarchy

## TL;DR

The study shows how the brain uses prior expectations to process faces, with some areas focusing on unexpected input and others sharpening expected information.

## Contribution

The paper provides empirical evidence for distinct neural mechanisms of prediction error and representation sharpening in face processing.

## Key findings

- Expected faces were identified faster and ambiguous faces were perceived in line with prior expectations.
- Prediction error processing was observed across the face-processing hierarchy from the OFA to the anterior temporal lobe.
- Sharpened representations were found specifically in the occipital face area.

## Abstract

The perception and neural processing of sensory information are strongly influenced by prior expectations. The integration of prior and sensory information can manifest through distinct underlying mechanisms: focusing on unexpected input, denoted as prediction error (PE) processing, or amplifying anticipated information via sharpened representation. In this study, we employed computational modeling using deep neural networks combined with representational similarity analyses of fMRI data to investigate these two processes during face perception. Participants were cued to see face images, some generated by morphing two faces, leading to ambiguity in face identity. We show that expected faces were identified faster and perception of ambiguous faces was shifted towards priors. Multivariate analyses uncovered evidence for PE processing across and beyond the face-processing hierarchy from the occipital face area (OFA), via the fusiform face area, to the anterior temporal lobe, and suggest sharpened representations in the OFA. Our findings support the proposition that the brain represents faces grounded in prior expectations.

Perception and neural processing of sensory information are influenced by prior expectations. Here the authors show investigate how prior expectations contribute to face processing in the brain.