Continuity and Change in Theory-of-Mind Development: A Neuroscientific Approach.

Abstract

This dissertation seeks a more comprehensive picture of the process of theory-of-mind development (an understanding that action is guided by internal mental states such as beliefs, desires, and intentions) by examining neurological correlates of theory-of-mind reasoning in child populations. Taken together, three studies, each using a different neuroscientific method, span investigations of early, middle, and late childhood, substantially increasing the currently small pool of pediatric neurocognitive research. The studies highlight the utility of a neuroscientific approach to theory-of-mind investigations, and illustrate the importance of collecting developmental data. Results exemplify how, when applied in the developmental context, neuroscientific methods shed light on open questions of continuity and change in theory-of-mind development, and how different mental-state understandings (e.g., beliefs and desires) build to form a complete theory of mind.

Study 1 uses fMRI and resting EEG methods to track theory-of-mind neural correlates longitudinally from 4- to 7-years-old. Results provide direct evidence for continuity and indirect evidence for change in the relation between theory-of-mind reasoning and neural substrates over early to middle childhood. Moreover, they provide validation for novel methodology that can advance theory-of-mind research in younger, and social-cognitively impaired populations. Study 2 uses fNIRS to investigate belief- and desire-reasoning in 7- and 8-year-olds. Results suggest a mechanism by which belief-understanding may build off prior desire-understanding, and demonstrate a method by which changes in these mechanisms can be measured as a function of performance accuracy. Study 3 uses ERP to examine neural correlates of belief- and desire-reasoning in 10- and 11-year-olds. Results provide important developmental comparisons to two prior, parallel ERP studies, to further illuminate the complex neurodevelopmental processes underlying advancement in belief- and desire-reasoning from middle to late childhood.

These studies allow cross-methodological comparisons, combining strengths to overcome weaknesses of any single method, and provide test cases for adapting neuroscientific methods for children. Theoretically, they pioneer in forming a comprehensive picture of how theory-of-mind mechanisms and conceptions change with time and experience, and further illuminate the processes governing theory of mind and its development.