False belief reasoning in pronoun resolution during on-line sentence processing

Theory of Mind (ToM) and language are closely related, yet few studies have examined the role of ToM during on-line sentence processing. To that end, we investigated ToM in pronoun resolution using self-paced reading. We constructed false-belief contexts where a protagonist was misinformed about the referent of a pronoun, true-belief contexts where he/she was correctly informed, and target sentences with a critical pronoun. A gender-mismatch effect was predicted in the True-belief condition but not in the False-belief condition if ToM was operative in sentence processing. This prediction was confirmed. Furthermore, target sentences were read more slowly after False- than True-belief contexts at word positions related to the mental states of the protagonist. These results suggest the importance of ToM during on-line sentence processing: comprehenders adopt the perspective of a protagonist to resolve pronoun ambiguity.