Speed of information processing after unilateral stroke.

Speed of information processing in the subacute stage after stroke was studied in 88 first ever, unilateral, ischemic stroke patients. The patient group included 42 right and 46 left hemisphere patients. Seventy-one control subjects were also examined. Four reaction time tasks with different levels of complexity were used: two visuomotor, and two semantic categorisation tasks. The results showed that stroke causes a decrease in decision making speed, but that the effect is different for right and left hemisphere patients. The right hemisphere group were slower than the control group on all reaction time tasks, and slower than the left hemisphere patients on the visuomotor tasks. The left hemisphere patients were slower than the healthy controls, only on the most complex tasks, the categorisation tasks.