Action sequencing deficit following frontal lobe lesions

Frontal lobe patients carried out temporal sequencing tasks related to actions that differed in terms of their abstractness using both verbal and pictorial presentations. A generalized impairment was found: neither a type of action effect nor a modality of item presentation effect was present. The patients also carried out a corresponding action production task and produced actions quickly and without errors. The frontal lobe patients were also spared in generating verbal descriptions of actions: they were as accurate as normal controls both in terms of the details reported and in maintaining the temporal sequence. It has been argued that the difficulty in processing the temporal dimensions of actions following frontal lobe lesions is due to some form of disruption of the action representation. However, no action representational deficits were present in our frontal lobe patients. Thus, they cannot account for our findings. On the contrary, we suggest that the action sequencing deficit was a consequence of the difficulties patients experienced in rejecting wrong alternatives presented by the stimulus situation.