Seeing others’ intentions in autism

Background: The ability to infer the intentions of others by observing their movements is crucial for social interactions. Children with autism spectrum disorders (ASD) are delayed in the development of this ability, with knock-on consequences across lifespan. Here we report on a study combining motion tracking, psychophysics and computational analyses to compare intention readout in typically developing (TD) children and children with ASD. Methods: Eight- to thirteen-year-old TD children (n=37) and ASD children without accompanying intellectual impairment (n=35) watched a hand reaching for a bottle, either to pour or to place, and judged on the intention of the observed grasp. In a within-subjects counterbalanced order, participants watched videos of actions performed by TD children and ASD children. Using a time-dependent logistic regression fitted to the experimental data, we analyzed how intention encoding – the mapping of intention to movement kinematics during action execution – and intention readout – the mapping of visual kinematics to intention during action observation – intersect at a single-trial level in TD children and children with ASD. Results: Whilst intention readout was sensitive to variations in visual kinematics in both groups, the proportion of individuals with intention readout sensitive to visual kinematics (‘readers’) was lower in the ASD group than in the TD group (p<.01). A significant proportion of TD readers was able to infer the correct intention, when observing both TD and ASD actions (ASD actions: p<.01; TD actions: p<.001). ASD readers failed to map visual kinematics to the correct intention regardless of whether they observed TD or ASD actions. Conclusions: Whilst observers with ASD are not blind to subtle variations in visual kinematics, they are unable to link such variations to the correct intention. These findings have implications for understanding how misalignment between intention encoding and readout impact social interactions in autism.