THE INSPECTION TIME NOT STUDIED - PROCESSING SPEED ABILITY UNRELATED TO PSYCHOMETRIC INTELLIGENCE

In two experiments (n = 178 and n = 190), spatial, quantitative, and verbal inspection-time (IT) and visual-search (VS) tasks were administered to the same subjects along with measures of general intelligence (IQ). IT tasks were length, numeracy, and letter-string classifications made difficult by backward masking. IT tasks used accuracy as a performance measure. VS tasks were searches of figural, numeric, or word targets in arrays of similar items. VS tasks used reaction time under a high accuracy set as a performance measure. In both experiments IT correlated significantly to both IQ and VS, and in both experiments the negative correlation of IT to VS was significant controlling for IQ. The results provide evidence that IT performance has a component related to IQ tests and an independent component related to other processing speed tests such as visual search.