Objectives: To explore the relationship between mentalising and executive impairments and their causal roles in the social symptoms of autism.

Methods: 57 children with ASD were compared to 27 normally-developing 7-12 year olds on a battery of tasks assessing verbal and non-verbal intelligence, mentalising abilities and executive dysfunction. The children also took part in direct and indirect measures of their everyday behavioural symptoms.

Results: Group differences were found on all mentalising and some executive tasks; approximately half of the children with ASD showed severe impairment in mentalising and a third in executive function. As expected, mentalising and verbal ability were highly associated within both groups, while mentalising and executive function were related only in the autism group. An additional surprising association between executive function and verbal ability was present in the autism group but this could not account for the relationship between mentalising and executive function. There was a tendency for children to display: mentalising and executive impairment, just mentalising impairment, or neither. The behavioural data indicated associations only between mentalising and social skills.

Conclusions: This pattern of results may indicate that executive failure is primary to mentalising difficulties. However, an alternative explanation could be that poor executive task performance might emerge from poor mentalising ability, which would also lead to impaired social skill. Indeed, an analysis of the errors made in the executive tasks revealed an unusual pattern of idiosyncratic or egocentric performance and suggested that impaired performance on executive tasks may result from difficulties forming an implicit understanding of the experimenter’s expectations for the task.