Reaction times and intelligence differences A population-based cohort study

Abstract

The association between reaction times and psychometric intelligence test scores is a major plank of the information-processing approach to mental ability differences. An important but unavailable datum is the effect size of the correlation in the normal population. Here we describe the associations between scores on a test of general mental ability (Alice Heim 4, AH4) and reaction times using a 'Hick'-style device. The sample is 900 people aged 56 years who are broadly representative of the Scottish population. AH4 Part I total scores correlated −.31 with simple reaction time, −.49 with four-choice reaction time, and −.26 with intraindividual variability in both reaction time procedures. The correlation between AH4 scores and the difference between simple and four-choice reaction time was −.15. Separate analyses were conducted after partitioning the total group according to sex, educational level, social class grouping, and number of errors on the four-choice reaction time task. None of these factors significantly altered the effect sizes. This is the first report of reaction time and psychometric intelligence in a large, normal sample of the population. It provides a benchmark for other studies and suggests larger effect sizes than the majority of present studies, which are dominated by young student samples.