Reaction Time in Brain-Damaged and Normal Subjects to Variable Preparatory Intervals

Reaction time performance in 20 brain-damaged Ss and 20 control Ss was studied, using a technique developed by Rodnick and Shakow, which employs preparatory intervals of 1, 2, 4, 7.5,15, and 25 seconds in length under both a regular and irregular presentation. The main results are: 1) brain-damaged Ss show significantly slower reaction times under each experimental condition examined; 2) for both the regular and irregular condition, the curves relating preparatory interval to reaction time are essentially the same for brain-damaged and normal Ss; and 3) a composite reaction time measure, the “set index,” does not achieve marked discriminative power in separating the two groups. In addition, it was found that the rate of development of the cerebral disease is a determining factor in slowing reaction time responses. The results of this study are discussed with references to reports on the same subject in the literature.