Understanding variability in processing facial expressions: Behavioural and neuroimaging studies

Abstract

The ability to perceive and recognise facial expressions of emotion is an important part of social communication. These processes are subject to influence from several internal and external sources of variance. The aim of the research within this thesis is to explore the relative contribution of some of these sources of variance on the processing of facial expressions. Under this broad aim, two main problems are addressed, using a combination of behavioural and neuroimaging methods in each. The first concerns the effect of observer age on the recognition of emotions from facial expressions. We showed that (1) older adults have poorer recognition of certain facial expressions than younger adults, and that these differences are explained by differences in several cognitive and visual measures, and (2) that the neural response to facial expressions attenuates across the lifespan. The second problem concerns the relative influence of stimulus-based cues and conceptual knowledge of emotions on behavioural and brain representations of emotion. Within this set of studies, we showed that perceptual similarity and confusability of facial expressions of emotion are explained by the similarity of face shapes, surface textures, and similarity of emotion concepts. In addition to behavioural measures, we found that these cues can explain representational similarity within several regions of the brain involved in the perception of facial expressions. Together, the results highlight several sources of variance affecting the processing of facial expressions of emotion in adults. These studies also pave the way for future research to investigate age differences from the perspective of differences in the role of conceptual and stimulus-based cues.