Belief Attribution Despite Heavy Verbal Interference In Autism

Background:

Theory of Mind deficit is one of the most influent theoretical explanations of autistic symptoms. Poor performances in false belief tasks (FBT) have been widely observed in subjects with autistic spectrum disorders (ASD), and are one essential argument for this account.

However, the paradox of high-functioning subjects with ASD passing FBT has led to a dual-processing explanation of belief representation including two hypotheses:

(1) An intuitive processing of beliefs in normal subjects and

(2) A deficit of this intuitive processing in autistics, with compensatory verbal reasoning in high-functioning subjects (Happé 1995).

In order to test (1), we designed the Belief Attribution Task (BAT), a completely nonverbal paradigm consisting of silent animated cartoons in five closely related conditions, systematically teasing apart different aspects of scene analysis and allowing the assessment of the attribution of beliefs, goals, and physical causation, respectively. We then used verbal shadowing as a dual task to inhibit inner speech and showed that typical adults remained able to attribute beliefs despite heavy concurrent demands on their verbal abilities, supporting hypothesis (1) (Forgeot d'Arc & Ramus, QJEP, in press).

Objectives:

In order to test hypothesis (2), we aimed to compare the effect of heavy verbal interference on the ability to attribute beliefs, goals and physical causation in adults with and without ASD.

Methods:

We used verbal shadowing to inhibit reasoning, during the BAT in high functioning adults with and without ASD.

Results:

In both groups, verbal interference decreases overall performance, but has no specific effect on belief Attribution. Participants with and without ASD remained able to attribute beliefs despite heavy concurrent demands on their verbal abilities.

Conclusions:

Contrary to (2), our results are most consistent with the hypothesis that belief attribution is independent from inner speech in high functioning adults with and without ASD.