Classification of facial expressions involves interpreting both the face and the context in which the face appears. Generally, it is believed that cues from the context influence the classification of facial expressions because the context shifts viewers’ perception of the face. However, we questioned the validity of this conclusion due to methodological limitations of past studies leading to it. Therefore, the first aim of this thesis was to examine whether contextual cues indeed shifted viewers’ perception of facial expressions. We carefully examined this using a recently developed psychophysical method that aims to isolate the contribution of perceptual processes to viewers’ behavioural responses about facial expressions. Second, we highlight that there is a considerable amount of variability in the extent to which different individuals experience the effect of context on classification of facial expressions. Accordingly, in this thesis, we also conducted a series of experiments to identify the source of such individual differences. In Chapters 2 and 3, we show that changes in classification of facial expressions that result from contextual cues (body gestures in our case) is not due to changes in the perception of the face. Accordingly, we claim that contextual effects on classification are the product of changes in post-perceptual (e.g., decisional) processes contributing to classification. In Chapter 3, we also demonstrate that both perception and classification of facial expressions shift in the direction of the emotion conveyed by the context, although the two effects appear to be independent of each other. The size of these shifts increased with greater disparity in emotion between how viewers perceive/classify isolated facial expressions and the emotion signalled by the context. We replicated this relationship for the classification of facial expressions in Chapters 4 and 5 as well, with large effect sizes. Based on this recurring effect, we claim that individual differences in how facial expressions (alone) are interpreted is a crucial determinant of individuals’ susceptibility to the influence of contextual cues. In Chapters 2 to 5, we also explored various other individual differences. We find that individual differences in the severity of clinical traits (autism, depression, alexithymia and anxiety), thinking styles (holistic and analytical), self-construals (independent and interdependent) and the deployment of overt attention between the face and context, do not account for the variability in the level of contextual effects experienced by our participants. Although we found in Chapter 4 that culture seems to play a role, with Western British participants experiencing larger contextual effects than Asians. We believe this was a result of Western participants’ greater familiarity with Caucasian faces and body gestures that we used as stimuli. Drawing on our findings, we propose a novel “seeds and conflict theory”, wherein the degree of conflict between an individuals’ subjective evaluation of the target facial expression and the representation of an expression activated by a context (i.e., primed) drives the strength of contextual influence. Accordingly, while existing theories of contextual effects (e.g., emotion seeds hypothesis) cannot explain some of our findings, in Chapter 6, we provide a critical evaluation of theories and show that our seeds and conflict theory can account for our findings across all empirical Chapters (2-5), as well as findings from previous studies in the literature.
Nathali Nimsha Nilakshi Lennon (Sat,) studied this question.