Disordered action schema and action disorganisation syndrome

We assessed the performance of four patients on a range of everyday tasks. Two patients were identified as having the symptoms of Action Disorganisation Syndrome (ADS) on the basis of their errors. The other two patients were matched to the ADS patients for short-term and longer-term episodic memory performance and for performance on the Stroop task. The ADS patients were selectively impaired both when carrying out the everyday tasks and when generating and ordering the necessary component subactions. These patients also had problems in following novel commands, though similar difficulties occurred in a patient with frontal lobe damage but without deficits on everyday tasks. In addition, different patterns of perseverative error arose in the two patients showing symptoms of ADS. We suggest that ADS can be caused by a disorder of action schema, and we discuss the different ways in which the retrieval of such schema can break down.