Inspection times and the selection task: Are they relevant?

Five experiments are reported based upon Evans' (1996) inspection time paradigm in which subjects are required to solve computer-presented Wason Selection Task problems while simultaneously using a mouse to indicate which card is currently under consideration. It had previously been found that selected cards were inspected for considerably longer than were non-selected cards, and this was taken as support for the existence of pre-conscious heuristics that direct attention towards relevant aspects of a problem. The first experiment reported here fully replicated this effect. However, by systematically varying the task format in subsequent experiments, the effect was found to diminish, disappear, or even reverse. The change in effect size and direction was not accompanied by any systematic variations in the subjects' card choices, indicating that the changes in task format had not altered the operation of the relevance-determining heuristics. On balance, it is suggested that the inspection time effect appears to be artefactual, and the inspection time paradigm therefore does not constitute satisfactory evidence for the existence of pre-conscious heuristics.