Doctor of Philosophy (PhD)


Linguistics (Interdepartmental Program)

Document Type



Modality is traditionally defined as the expression of possibility or necessity. In English, modality is expressed by the modal auxiliaries such as can, would, should, or might; adjectives and adverbs such as possible, necessary, maybe, and absolutely; or phrasal verbs such as going to or have to. Theory of Mind (ToM) is broadly defined as the ability to attribute thoughts and beliefs to other people. ToM is usually expressed using propositional attitude verbs such as think as in Mary thinks that it will rain. Hegarty (2006, 2010) proposes that propositional attitude verbs are covertly modalized and can be analyzed using the same apparatus as modals. If this theory is correct, then attitude ascriptions that are used to express ToM should be acquired by children after the child has a command of modality. Previous research shows that modality emerges in children as young as two years of age (Choi, 1999), but that children do not reach adult proficiency until around twelve years of age (Coates, 1987). Similarly, ToM begins to emerge when children can pass the standard false belief task near their fourth birthday (Wimmer & Perner, 1983; Baron-Cohen, Leslie & Frith, 1985), but children lack the necessary interpretation of the thoughts and beliefs of other people until they are approximately twelve years old (Lalonde & Chandler, 2002). This study evaluates the acquisition of both modality and ToM in eighty-six first, third, and fifth graders, using elicitation tasks for modality and question-answer tasks to test for higher-order ToM. The data was then analyzed indicating the approximate age of the acquisition of different types of modality such as epistemic (both strong and weak), alethic, priority, and dynamic. These results were then compared to those of the ToM tasks which indicate the age at which first, second, third, and fourth order ToM are acquired. The data suggests that modality and ToM are interdependent. Based on the results, a strong sense of modality emerges before the appropriate use of expressions of the second-order ToM, and third and fourth order ToM are mastered before the more difficult expressions of modality.



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Committee Chair

Hegarty, Michael

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Linguistics Commons