Long and short term memory in head injured patients.

A group of severely head injured patients were compared with 15 controls on auditory vocal digit span, and on a free recall memory task, enabling short term memory (STM) and long term memory (LTM) to be examined. The free recall curves differed for the two groups suggesting that the head injured patients had an essentially normal STM, but a poor LTM. This was supported by the finding of a significantly lower number of semantic errors (presumably retrieved from LTM) and a normal digit span (STM) in the head injury patients. The severity of the injury as judged by post-traumatic amnesia or the presence of neurological signs at the time of memory testing showed only a weak relationship to the severity of the memory deficit. The presence of a skull fracture was of minor importance in determining the severity of the LTM defect. Patients tested early after the injury were significantly poorer on STM, but not on LTM.