Structural alignment facilitates the noticing of differences

High-similarity concept pairs that elicit many commonalities also elicit ma ny related differences (Gentner & Markman, 1994; A. B. Markman & Gentner, 1 993a, 1993b, 1996; A. B. Markman & Wisniewski, 1997). This finding has been used to support the claim that the comparison process is one of structural alignment. However, it is possible that the difference advantage results f rom some other property of high-similarity pairs, such as a greater number of stored differences. The present experiments demonstrate that the compari son process itself leads to the greater psychological availability of diffe rences. In three experiments, participants listed commonalities for word pa irs and then listed differences under a time pressure for these old pairs a nd new pairs. In Experiment 1, participants listed more differences for old than for new pairs, consistent with the claim that the comparison process facilitates noticing differences. In Experiment 2, we showed that the diffe rence-listing advantage is specific to the comparison process: Mere coproce ssing of the pairs (specifically, providing thematic relations) does not fa cilitate, and in fact appears to inhibit, difference listing. In Experiment 3, pairs with deeper common systems elicited a larger number of specific a lignable differences than did pairs with shallow sets of commonalities. Ove rall, the results support the structural alignment claim that the compariso n process promotes the noticing of both commonalities and related differenc es.