An information processing approach to cognitive recovery following closed head injury
The aim of this thesis was to investigate cognitive recovery following closed head injury within an information processing approach. Reasons why Clinical Neuropsychology has neglected the potential contribution from experimental psychology were outlined. Relevant head injury variables were reviewed. including the cognitive deficits often associated with such damage and their recovery. A pilot study confirmed that head-injured people, even soon after injury can attempt tasks with a high information processing load. The study covered the first six months post-injury using mild/moderate and severe head-injured subjects (total n=12). the findings indicating slower performance in severe subjects and their greater susceptibility to interference from irrelevant information. The central focus of the thesis was Sternberg's Memory Scanning Paradigm and this was described in detail. The relevant literature was discussed in depth including both general and clinically-relevant studies. Although pertinent studies are scarce, brain damage appears to slow memory scanning speed, differential effects being suggested according to severity of damage. In the main study a sample of head-injured subjects (n=42) was followed-up longitudinally at 1, 3, 6, 12, 24 and 36 months post-trauma. A second patient sample (n=10) was also tested at 24 and 36 months after injury. to allow a long-term follow-up "back-up" in case of excessive drop-out. A control sample (n=10) of normal volunteers was also tested. In addition to memory scanning performance patient subjects were also tested on a number of other clinical memory tests (Rey AVLT, digit span, WMS) and subjective memory questionnaire data were also obtained. Findings pointed to a slowing of memory scanning ability after head injury, the degree of dysfunction being most marked in subjects who had sustained an extremely severe head injury. Evidence of cognitive recovery was noted in some patients beyond 12-24 month post-injury. Significant associations between memory scanning performance and other memory measures were observed and a number of clinical variables were also examained. The findings were discussed in detail and a (primarily attentional) model was proposed to describe memory scanning and its dysfunction in head injury.