Reaction time and intelligence in the mentally retarted

Mildly retarted young adults were given simple and choice reaction time (RT) tests. Scores were also obtained on the Raven Progressive Matrices and the Figure Copying Test. Subjects' RTs increased as a function of stimulus complexity, and they were consistently subjects' intraindividual variability of response time was also markedly greater than that of non-retarded subjects. A number of RT parameters were found to be related to the measures of intelligence. Subjects seen on ten successive days showed low day-to-day stability of RT but no practice or fatigue effect.