[An analysis of simple reaction time in mentally retarded and nonretarded children matched on mental age: examination using intertrial interval as a variable].

The simple reaction times (RTs) in mentally retarded children and nonretarded children matched on mental age (MA) were analyzed, and the relationship between mental ability and RT performances was discussed. RTs in both groups were obtained under three temporal conditions. In Experiment I, it was found that: (a) The shorter intertrial interval (ITI), the shorter RTs in both groups and (b) in the retarded group, RTs of MA5 and MA6-8 subjects were significantly different, presumably because of motor and/or sensory disabilities in the younger subjects, irrelevant to mental ability. In Experiment II, different response characteristics were found for both groups under the complex temporal condition. Retarded subjects showed remarkably slow RT only on those trials in which a long ITI was followed by a short ITI. Nonretarded subjects had remarkable variation in RT over all trials. It was inferred that different psycho-behavioral characteristics of the subjects of both groups were reflected in the different response tendencies observed.