Inspection Time and Intelligence: Practice, Strategies, and Attention

Prior studies have shown that Inspection Time (IT) is moderately correlated with IQ. Typically, investigators have asserted that a shared mental speed factor is responsible for this correlation. Three experiments examined the effects of practice, response strategies, and attentiveness on inspection time and its relation to IQ. Results from Experiment 1 illustrated that IT improves over occasions and that, with improvement, the strength of the IT–IQ correlation is attenuated. Using accuracy rates from the longest stimulus durations in the IT task as an index of attentiveness, results from Experiment 2 suggested that attentiveness is at least in part responsible for the IT–IQ correlation. Although results from Experiment 3 further suggested that attentiveness contributes to individual differences in IT, the results also suggest that other processes, perhaps related to mental speed, contribute to the IT–IQ correlation.