Eye Tracking Reveals Impairments in Implicit Mentalizing in Adults with Asperger's Disorder

Background: Paradigms now exist that demonstrate that preverbal children anticipate others' actions based on their false beliefs well before they can understand standard False Belief tasks. One such paradigm using eye tracking has recently shown that children with ASD, aged 6 to 8 years, who fail explicit false belief tasks, also lack the implicit mentalizing ability demonstrated in preverbal children. What about adults with Asperger's Disorder who pass explicit false belief tasks? Would they nevertheless lack the implicit and spontaneous ability to mentalize? Eye tracking methodology can answer this question. However, the relevant paradigms have never been tried with adults.

Objectives: To test the hypothesis that adults with Asperger's Disorder, while passing explicit false belief tasks, will still show an implicit and spontaneous deficit in mentalizing. Specifically, whether they would fail to anticipate actions based on others' false beliefs, as revealed by their eye gaze.

Methods: We presented video stimuli of an actor watching an object being hidden in a box. The object was then displaced while the agent was not attending. We recorded participants' eye movement with an eye-tracker while they watched the agent's subsequent action and coded whether participants spontaneously anticipated the actor's behaviour (i.e. reaching for the location where the agent had last seen the object), which could only have been predicted based on her false belief. 19 adults with Asperger's Disorder, (IQ above 85) as well as 17 neurotypical adults, participated in this study. The study was approved by the UCL Research Ethics Committee. Participants gave informed written consent.

Results: Neurotypical adults anticipated (by looking at the window through which she would reach) the agent's action based on her false belief (p < .05, binominal test). Asperger adults did not show such anticipatory looking (p > .1, binominal test). In addition, neurotypical adults spent significantly longer looking at the correct location than Asperger adults (F (1,32) = 4.93, p < .05, η_p² = .134).

Conclusions: Eye tracking revealed that adults with Asperger's Disorder, despite being able to take into account others' mental states when explicitly required to do so in standard verbal tasks, lacked the spontaneous and implicit ability to anticipate other's actions in non-verbal False Belief tasks.