Abstract
This thesis aimed to examine the contributors to social understanding across the lifespan by conducting three studies focusing on different developmental periods: (1) the preschool years when young children reach a false-belief milestone, (2) middle childhood and adolescence when children’s social understanding continues to improve, and (3) later adulthood when there are declines in both general cognition and social understanding.
In Study 1, I examined the contributions from maternal mental state talk to ToM in two distinct cultures by comparing 271 mother-child dyads from New Zealand, Australia, and China. I asked mothers to describe pictures to their 2.5- to 5-year-olds and coded their mental state talk in terms of quantity (e.g., frequency) and quality (e.g., variety). There were clear cultural differences, with more and richer (greater variety of words) mental state talk in Australia and New Zealand than China. There was also a link between maternal attitudes (e.g., social dominance orientation and authoritarian attitude) and children’s ToM, but a weak relation between maternal mental state talk and ToM. A longitudinal study is needed to further examine whether the cultural contrasts in mental state talk account for differences in children’s ToM in future research.
In Study 2, I examined the contributors to ToM in middle childhood and adolescence by using a new task – the Mr Bean task. I presented a wordless video to 80 children (6-16 years) and 49 young adults (18-22 years) and asked them to interpret the characters’ behaviour with or without referring to mental states. ToM continued to improve over this period into adulthood, and the improvement correlated with vocabulary, but not fluid intelligence. That is, language continued to play a central role on ToM development across middle childhood and adolescence, just as in the preschool years.
In Study 3, I examined general cognition as a contributor to the decline of social understanding in old age. I gave 47 young and 40 older adults three tasks to assess general cognition (processing speed, working memory, fluid intelligence) and three tasks to assess their social understanding (emotion and theory-of-mind). Older adults showed difficulties in all these abilities compared to younger adults. There were correlations between general cognition and social understanding, but older adults were still worse on the measures of social understanding than young adults after accounting for general cognition.
To conclude, this thesis provided a broad picture of social understanding development beyond the preschool years and highlighted the importance of social, cognitive, and linguistic contributors (e.g., mental state talk, language, and general cognition, etc.) that play essential roles in developing an understanding of mental states. I suggested future studies to extend the scope of research by exploring a wider age range, examining different cultures or more neurodivergent samples.