The choice to cooperate or compete with others confronts us on a daily basis, and it is plausible that we use our mentalising skills to aid decision-making in such situations. We investigated the relationship between mentalising and decision-making in the prisoner's dilemma in
adults with autism spectrum disorders (ASD), who show impaired mentalising, and normal adults. After completion of three versions of the prisoner's dilemma, we conducted a semi-structured interview. This interview attempted to elicit a participant's spontaneous strategy when playing
each version of the game, as well as on their conception of the nature and strategy choice of their opponents (human vs. computer). Contrary to expectations, the behavioural choices of the adults with and without ASD were quantitatively similar, as were the qualitative responses to questions
used in the interview. The consistency of the evidence from both measures suggests that mentalising ability was not involved in selecting the choices made in these prisoner's dilemma tasks. Instead they suggest the hypothesis that a purely logical strategy may have been adopted. The introspections
of at least a subgroup of high-functioning individuals with ASD can on the whole be trusted and this use of mixed methods strengthens the validity of the conclusions drawn.