Engaging Nonverbal Theory-of-Mind Boosts Novel Word Retention in Adults

Previous research has argued that theory-of-mind (ToM) plays a critical role to motivate early language acquisition.Vocabulary learning is a lifelong journey from infancy to adulthood. As ToM and vocabulary grows in tandem through development, little is known whether ToM continues to be important for word learning in adults, and if so, whether there is a causal interplay between the ToM state and adults’ word learning outcomes. This study tests whether engaging nonverbal ToM assists novel word encoding and retention. We examined young adults (N = 51)’ word learning outcomes for meanings that were either introduced in a word-to-world direct mapping context or a pragmatically inferred context. Preceding each block of word learning for each context was a brief, nonverbal animation that either primed the ToM system or did not engage ToM. We found that initial meaning mapping via pragmatic inference was assisted specifically by priming ToM prior to word learning. Furthermore, word retention, tested 20 minutes after initial encoding, was strengthened for both pragmatically inferred and directly mapped words, when learning was preceded with a ToM video, as opposed to a non-ToM video. These results demonstrate that ToM causally interacts with word learning processes and facilitates both encoding and retention. Our findings strengthen previous arguments that ToM plays a critical role in language development and broaden this to encompass lifelong vocabulary learning.