Correlation between reaction time and intelligence in psychometrically similar groups in America and India

The relationship between psychometrically tested reasoning ability, or general intelligence (Raven's Progressive Matrices), short-term memory (forward and backward digit span), and measures of reaction time (RT), including visual and auditory simple RT and four degrees of choice RT, was investigated in groups of unskilled workers, mostly of below average, borderline, or retarded mental ability, selected in the United States and in India. Both groups showed parallel phenomena with respect to the relative difficulty of the various RT tests, their factor structure, and their theoretically expected correlations with psychometric intelligence, although the correlations were lower (and generally nonsignificant) in the Indian group, most likely because of this group's greater restriction in range of ability. The findings, overall, are consistent with other recent studies of RT and intelligence, which indicate that our standard IQ tests reflect basic cognitive processes, particularly speed of information processing, involved in individual differences in intellectual ability, and not merely differences in specific acquired knowledge, skills, or cultural background.