Date of Completion


Embargo Period



Dr. Jennie Pyers, Dr. Rhiannon Smith, Dr. Letitia Naigles

Field of Study



Master of Arts

Open Access

Open Access


Theory of Mind (ToM) abilities, i.e., the understanding that others’ internal states differ from one’s own, and that these states guide behavior, are multiply determined. ToM abilities underlie later social and pragmatic abilities, grossly affecting later life experiences, particularly for deaf children. However, previous studies have not clearly identified the effects of language, hearing status, or other exogenous factors, such as education or executive function abilities, on ToM development. To disentangle these, we studied three understudied populations in Nicaragua: Homesigners, who have not acquired a conventional language but have developed gestural communication systems; users of Nicaraguan Sign Language, an emerging language (NSL-Signers); and Unschooled Spanish Speakers (USS). Comparing these groups can help uncover the relative contributions to ToM of social experience (available to all groups), membership in a linguistic community (NSL-Signers and USS only), and education (only NSL-Signers).

Using a minimally verbal ToM protocol in which participants experienced two types of False-Belief: Unexpected-Contents and Appearance/Reality; an Inhibitory-Control task; two perspective-taking tasks; and a memory span task, we found: 1) Language was related to success on False-Belief measures of ToM as well as to transformational memory span, while 2) Education was related to success on conflict-Inhibitory-Control tasks. Performance on non-transformational memory span tasks, non-conflict-Inhibitory-Control, and Perspective-Taking did not differ across groups, suggesting that those without education or language community nevertheless develop these cognitive abilities.

The results suggest a complex interaction among language, inhibitory control executive function, and education for Theory of Mind Development, and highlight language as a necessary factor.

Major Advisor

Dr. Marie Coppola