Feature-specific prediction errors for visual mismatch

Abstract

Predictive coding (PC) theory posits that our brain employs a predictive model of the environment to infer the causes of its sensory inputs. A fundamental but untested prediction of this theory is that the same stimulus should elicit distinct precision weighted prediction errors (pwPEs) when different (feature-specific) predictions are violated, even in the absence of attention. Here, we tested this hypothesis using functional magnetic resonance imaging (fMRI) and a multi-feature roving visual mismatch paradigm where rare changes in either color (red, green), or emotional expression (happy, fearful) of faces elicited pwPE responses in human participants. Using a computational model for learning and inference, we simulated pwPE trajectories of a Bayes-optimal observer and used these to analyze changes in blood oxygen level dependent (BOLD) responses to changes in color and emotional expression of faces while participants engaged in a distractor task. Controlling for visual attention by eye-tracking, we found pwPE responses to unexpected color changes in the fusiform gyrus. Conversely, unexpected changes of facial emotions elicited pwPE responses in thalamo-cortico-cerebellar structures associated with emotion processing. Our results support a general role of PC across perception, from low-level to complex and socially relevant object features, and suggest that monitoring of the social environment occurs continuously and automatically, even in the absence of attention.\n\nHighlightsPredictive coding (PC) implies that brain responses should reflect transient precision weighted prediction errors (pwPEs). By using fMRI we show that rare changes in color or emotional expression of human faces elicit pwPE responses in dedicated neuronal circuits with known specialization in processing color and emotion-related information, respectively. Our results demonstrate that physically identical stimuli elicit pwPEs in distinct neuronal circuits when different (feature-specific) predictions are violated, depending on current sensory expectations based on prior stimulus context. The demonstration of pwPEs in visual areas as well as in emotion processing structures lends experimental support to theoretical accounts of PC in color and social perception, respectively.