Frontal and parietal lobe involvement in the processing of pretence and intention.

We assessed whether different processes might be at play during pretence understanding by examining breakdowns of performance in participants with acquired brain damage. In Experiment 1 patients with frontal or parietal lesions and neurologically intact adults were asked to categorize videos of pretend and real actions. In Experiment 2 participants saw three types of videos: real intentional actions, real accidental actions, and pretend actions. In one session they judged whether the actions they saw were intentional or accidental, and in a second session they judged whether the actions were real or pretend. Parietal patients had particular difficulties in the identification of pretend actions, and both parietal and frontal patients were more impaired than controls in understanding the intentional nature of pretence. Analyses of individual patients' performance revealed that parietal lesions, and in particular lesions to the temporo-parietal junction, impaired the ability to discriminate pretend from real actions. However, this did not necessarily affect the discrimination of intentional from unintentional actions, which instead may be independently disrupted by damage to frontal areas. Moreover, spared ability to discriminate pretend actions from real actions, and intentional actions from accidental actions, did not grant a full conceptual understanding of the intentional nature of pretence. The implications for pretence understanding are discussed.