Content memory and temporal memory for actions in survivors of traumatic brain injury

Memory for performed actions, a rehearsal-independent form of memory, was compared to verbal memory in 30 survivors of traumatic brain injury (TBI) and 30 demographically matched controls. Subjects were tested on recognition and recall memory for the content of recently performed actions in the laboratory, as well as the ability to reconstruct the temporal order in which the actions were performed. Each subject performed actions under incidental and intentional memory instructions. Half of the subjects performed 12 actions, the other half 24 actions, with an equal number of usual and unusual actions in each list. Verbal memory was assessed with paired-associate and temporal order tests. Although recall was more proficient overall for the control compared to the brain-injured subjects on both content and temporal memory for actions, memory for actions was better than verbal memory in both groups. Both groups performed better overall on the short compared to the long list of actions and recalled unusual actions better than usual actions. The rehearsal-independent nature of action memory was supported, with no advantage for the intentional instruction. It is proposed that a retrieval deficit may be in part responsible for deficits in memory for actions following TBI. However, preserved ability to benefit from the abundant contextual cues available through motor actions may account for the better recall of actions compared to words.