Predictive responses in the Theory of Mind network: A comparison of autistic and non-autistic adults

Social cognitive processes, particularly Theory of Mind (ToM) reasoning, appear to differ between autistic and non-autistic individuals. This has been proposed to reflect the autistic core symptomatology of communication and social interaction difficulties. According to the predictive coding theory, autistic individuals' ToM reasoning difficulties arise from an attenuated use of prior information about others' mental states to explain and predict their behavior. This reduced use of prior assumptions makes the social world less predictable for autistic people, causing interactive mismatch and stress. Despite strong theoretical claims, robust and replicable neural differences in ToM brain regions remain elusive. Here, we investigated whether brain regions supporting ToM reasoning anticipate a narrative during repeated exposure (i.e., the narrative anticipation effect) in non-autistic adults (Experiment 1) and tested whether this effect was attenuated in autistic adults (Experiment 2). We presented a short movie with a plot including mental states with associated actions, twice, to 61 non-autistic adults who underwent functional magnetic resonance imaging [Experiment 1: M(SD)_age = 25.9(4.4) years]. In Experiment 2, we used the same protocol with 30 autistic [M(SD)_age = 32.4(10.7) years] and 30 non-autistic adults [M(SD)_age = 33.2(10.1) years]. Analyses revealed no narrative anticipation effect in the ToM network in either group. Exploratory reverse correlation analyses identified a ToM scene that evoked a smaller difference in response between movie viewings (i.e., less repetition suppression) in autistic adults, compared to non-autistic adults. In sum, our study shows that predictive processing in the ToM network during a naturalistic movie-viewing experiment was absent in adults. Subtle differences in a key scene provide preliminary neural evidence for the predictive coding theory and open a promising avenue for future research to better understand the nature of differences in social interaction in autistic adults.