Predictability Modulates the Early Neural Coding of Spatially Unattended Fearful Faces

Abstract

In this study, we assessed whether predictability affected the early processing of facial expressions. To achieve this, we measured lateralised early- and mid-latency event-related potential associated with visual processing. Twenty-two participants were shown pairs of bilaterally presented fearful, happy, angry, or scrambled faces. Participants were required to identify angry faces on a spatially attended side whilst ignoring happy, fearful, and scrambled faces. At the beginning of each block, the word HAPPY or FEARFUL appeared informing participants the probability of the appearance of happy and fearful faces. Only effects of attention were found for the lateralised P1, suggesting that emotions do not modulate the P1 differentially, nor do predictions relating to emotions. Pairwise comparisons demonstrated that, when spatially unattended, unpredicted fearful faces produced larger lateralised N170 amplitudes compared to predicted fearful faces and unpredicted happy faces. Finally, attention towards faces increased lateralised EPN amplitudes, as did both fearful expressions and low predictability. Thus, we demonstrate that the N170 and EPN are sensitive to top-down predictions relating to facial expressions. Furthermore, low predictability appears to affect specifically the early encoding of fearful faces, such that when attention is engaged elsewhere, the low predictability of a fearful face enhances early encoding processes, possibly to initiate attentional capture.