Emotion processing and the broader autism phenotype

Abstract

The processing of emotion is fundamental in various aspects of human experience. However, our understanding of emotional processes is incomplete, particularly in relation to language processing. Further, individuals such as those with an autism spectrum disorder (ASD) often show differences in their perception and understanding of emotion. Whilst many characteristics of ASD present to varying degrees in the wider population, the extent to which differences in emotion processing extend beyond those with a diagnosis of ASD remains largely unknown. The aims of this thesis were to determine the links between emotion and language processes in both adults and children, and to determine the relationship between emotion processing and non-clinical levels of autism-like traits, known as the broader autism phenotype (BAP). These aims were achieved by investigating (i) the recognition of facial and vocal emotional cues in relation to autism traits, and (ii) the impact of emotional cues on language learning in relation to autism traits.Chapter 2 aimed to determine how vocal expressions of emotion influenced subsequent recognition of facial emotions, and whether this influence differed according to levels of autism-like traits among typical adults. The results revealed that emotions, expressed via a combination of semantic meaning and prosody, enhanced subsequent facial emotion recognition when the vocal and facial cues were congruent, and impaired recognition when the emotional cues were incongruent. However, these effects were apparent only for those with low levels of autism-like traits and not for those with higher levels.Chapter 3 aimed to determine whether typically developing children were able to match various vocal expressions of emotion to facial expressions, and whether this ability differed between those with low or high levels of autism-like traits. The results showed that the children’s ability to match emotions differed according to emotion type, such that more errors were made when matching expressions of happiness and fear, compared to sadness and anger. However, matching ability did not differ between those with low or high levels of autism-like traits.Taken together, the results of the two studies outlined in Chapters 2 and 3 indicated that adults with higher levels of autism-like traits failed to integrate emotional information across modalities. However children with higher levels of autism-like traits were able to integrate cross-modal emotional information in a similar manner to those with lower levels of autism-like traits. These findings suggest that difficulties integrating emotional information across modalities may be characteristic of the BAP, but may become apparent between mid-childhood and adulthood.Chapter 4 aimed to determine whether vocal emotional cues impacted adults’ ability to learn new words, and explored whether this ability to learn was influenced by levels of autism-like traits. The results revealed that fearful prosody interfered with the ability to learn new words for all participants. Further, happy prosody also interfered with the ability to learn new words, but only for those with lower levels of autism-like traits, and not for those with higher levels of autism-like traits.Chapter 5 explored whether emotional cues influenced word learning ability in children who had either low or high levels of autism-like traits. Eye-tracking measures were also used to determine children’s visual attention relative to emotion type and autism-like traits. The results showed that emotional information did not influence word learning ability. However, different patterns of visual attention emerged between those with low and high levels of autism-like traits. Specifically, children with lower levels of autism-like traits showed the same looking patterns when viewing happy and fearful emotions, which were distinct from their looking patterns in the neutral condition. However, children with high levels of autism-like traits showed distinct looking patterns between the happy and fearful conditions.These studies (Chapters 4 and 5) indicate that, while emotional information was somewhat distracting for all adults during word learning, adults with higher levels of autism-like traits were affected differently according to the type of emotion. Similarly in children, although emotion had no behavioural effect on learning, children with high autism-like traits were affected differentially according to emotion type, while those with low autism-like traits responded equally to both emotions. This finding suggests that differences in the processing of positive and negative emotions within a language learning context may be characteristic of the BAP, and this may have a cumulative impact on learning throughout development.Overall, the thesis results suggest that links between the processing of emotion and the BAP are more pronounced in adulthood. The findings have implications for our understanding of ASD, with respect to its underlying risk factors and characteristics. In addition, this thesis provides insight into the development of emotion processing and individual differences within typical populations.