WORKING-MEMORY AND SUPERVISORY CONTROL AFTER SEVERE CLOSED-HEAD INJURY - A STUDY OF DUAL-TASK PERFORMANCE AND RANDOM GENERATION

Survivors of severe closed-head injury (CHI) frequently suffer from sl owed information processing. Whether supervisory strategies are additi onally impaired remains a point of debate. The first part of this stud y employed a self-paced dual task; the second part, a random generatio n task, performed at a paced rate, under single and dual task conditio ns. A measure of information processing speed was used as a covariate in statistical analysis. In the first experiment, in addition to slow processing, patients performed slightly poorer than controls on each t ask. In the second experiment, patients' performance (one randomness i ndex in single task condition, and processing of dual task) was impair ed even after statistical control of slow processing. These results su ggest that there is at least some degree of impairment in supervisory strategies in addition to, but independent of, slowed processing. The clinical significance of this finding is discussed.