IQ, Inspection time, and response strategies in a university population

Abstract

The relationship between Inspection Time (a perceptual discrimination task designed to estimate the rate at which a subject processes sensory input) and the Wechsler Adult Intelligence Scale (WAIS) was assessed in a sample of 29 university students. Sixteen of the subjects (“strategy users”) independently developed a strategy for performing the task, based on apparent movement cues. The remaining 13 (“non-users”) did not develop the strategy and could not easily be trained in its use. Strategy users had slightly faster Inspection Times than non-users, but were not significantly different from the non-users on the WAIS or any of the subtests. However, the two groups differed substantially in the relationship of Inspection Time to IQ. In the strategy users, Inspection Time was not significantly related to IQ or to any of the WAIS subtests. In the non-users, Inspection Time was highly correlated with Performance IQ and with scores on two of the subtests. Methodological implications of the differences between strategy users and non-users, and the theoretical status of Inspection Time as a measure of mental speed, are discussed.