Sustained attention to visual and auditory stimuli and reflection-impulsivity were examined in 48 hyperactive and 48 normal 9 and 14 year old boys. Multivariate analyses, followed by univariate tests, indicated that the nonhyperactive Ss increased sustained attention efficiency with age to both visual and auditory Stimuli. Hyperactive Ss increased in sustained attention efficiency with age to auditory, but not visual stimuli. Both groups increased with age in reflection-impulsivity as measured by the Matching Familiar Figures (MFF) test. Correlations between the sustained attention scores and the MFF error and latency scores were not significant for hyperactive Ss. (Author)