Impulsivity and Overall Similarity Classification

It is sometimes argued that implementation of an overall similarity classification is less effortful than implementation of a single-dimension classification. One piece of evidence taken to be in support of this argument is that highly impulsive individuals appear to be more likely to sort on the basis of overall similarity than individuals with low impulsivity (Ward, 1983); presumably, higher impulsivity results in lower effort. In the current article, we identify some limitations in Ward’s procedure and, using a more standard measure of impulsivity and a less ambiguous measure of overall similarity classification, re-investigate the relationship between impulsivity and overall similarity classification. Using a match-tostandard procedure, the current experiment finds that overall similarity classification is less prevalent in highly impulsive individuals. The implications of this result, which is opposite to that reported by Ward (1983), are discussed.