Testing the domain-specificity of a theory of mind deficit in brain-injured patients: Evidence for consistent performance on non-verbal, “reality-unknown” false belief and false photograph tasks

To test the domain-specificity of “theory of mind” abilities we compared the performance of a case-series of 11 brain-lesioned patients on a recently developed test of false belief reasoning (Apperly, Samson, Chiavarino, & Humphreys, 2004) and on a matched false photograph task, which did not require belief reasoning and which addressed problems with existing false photograph methods. A strikingly similar pattern of performance was shown across the false belief and false photograph tests. Patients who were selectively impaired on false belief tasks were also impaired on false photograph tasks; patients spared on false belief tasks also showed preserved performance with false photographs. In some cases the impairment on false belief and false photograph tasks coincided with good performance on control tasks matched for executive demands. We discuss whether the patients have a domain-specific deficit in reasoning about representations common to both false belief and false photograph tasks.