The well-known hypothesis of Sir Francis Galton (1883) posed that individual differences in performance on diverse sensorimotor tasks are rooted in single general sensory discrimination ability. Relatedly, Charles Spearman (1904) hypothesized that this discrimination ability and intelligence share the same neural basis and thus should be statistically equivalent. Despite a century of research, existing evidence for these 2 hypotheses is still inconclusive. Study 1 modeled the factor structure for, to date, the most comprehensive battery of tasks tapping into visual discrimination, and investigated its relationships with iconic and working memory, as well as intelligence. The confirmatory factor analysis (CFA) and structural equation modeling (SEM) models indicated that performance could be grouped into 2 considerably correlated, yet statistically separate factors reflecting temporal versus nontemporal (i.e., featural) sensory discrimination ability. These 2 abilities correlated considerably with working memory and intelligence but, at the same time, were clearly separable. However, the discrimination–intelligence link disappeared when mediated by working memory, suggesting that sensory discrimination plays no explanatory role in intelligence. In Study 2, the above findings were supported and extended by introducing auditory discrimination tasks. The results indicated 3 independent factors reflecting: amodal temporal discrimination, visual featural discrimination, and auditory featural discrimination. Working memory (WM) fully accounted for the shared variance among the three abilities and their relationships with intelligence. Overall, both Galton and Spearman validly guessed that various low-level sensorimotor processes can be mutually linked but, contrary to their ideas, sensory discrimination neither constitutes unitary ability nor is equivalent to intelligence.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.