In a study of the relationship between speed of information processing and general intelligence, vocational college students (50 black males and 56 white males) took eight different reaction time tests measuring the speed with which individuals perform various elementary cognitive processes, and a group test of scholastic aptitude (the Armed Services Vocational Aptitude Battery, or ASVAB). Findings of the study were: (1) there was a moderate correlation between the cognitive tasks and the ASVAB; (2) in a comparison of the vocational students' results with those of university students with higher average academic aptitude tested in an earlier study, the latter performed significantly faster and showed less intraindividual variability; and (3) in a comparison between the black students and the white students, the white group overall obtained higher scores on the ASVAB and performed more quickly on the cognitive tests. In both sets of comparisons, there was a close correspondence between the relative complexity of the cognitive tests and the differences in group responses. In conclusion, the results of this study are consistent with the hypothesis that individual differences and the mean differences between groups in psychometric abilities and scholastic achievement are related to differences in the speed of information processing as measured in elementary cognitive tasks. (CMG)