Reaction time and coincidence anticipation performance of retarded and nonretarded subjects

The purpose of this study was to examine reaction time (RT) and coincidence anticipation (OA) performance across an age range of 7-20 years for retarded and nonretarded subjects. An attempt was made to determine whether one or all of the following existed: (a) a developmental pattern of decreasing RT and decreasing CA error scores with increasing age, (b) similar RT and CA performance for retarded and nonretarded subjects at each age level, and (c) a significant relationship between RT and CA performance for any of the various age and IQ combinations.

Eighty male subjects were selected from one of two populations: (a) retarded (IQ range of 50-69, inclusive) and (b) nonretarded. Twenty trials were administered to all subjects on both a simple visual reaction time task and the Bassin Anticipation Timer. Variable foreperiods were randomly assigned to RT trials and a stimulus velocity of 134 cm/sec (1.7 sec, viewing time) was used for the CA trials. Dependent measures (calculated on the data from trials 7-16 on each task) were median RT and median constant error (CE), and variable error (VE) which was the standard deviation of a subject's CE scores around his median CE. The Kruskal-Walliis one-way analysis of variance was used to test for significant differences; and, the Mann-Whitney-Wilcoxen technique was performed, where appropriate, to locate the source of those differences. The Spearman rank correlation procedure was used to determine the strength of relationship between RT and the absolute value of median CE scores.

The results suggested that (a) RT decreases over age for both nonretarded and retarded subjects, (b) the slower RT of retarded subjects when compared with that of nonretarded subjects is more pronounced at younger ages (7, 9, 11 year olds), (c) both retarded and nonretarded subjects demonstrate a slight positive CE bias (i.e., late response) in CA performance, (d) VE decreases over age for both nonretarded and retarded subjects, (e) except for the oldest nonretarded group, there is no significant relationship between RT and CA performance.