Abstract
Topic importance and set size of similar or dissimilar attitude have been shown to have some impact on interpersonal attraction in within-subject design studies, but have no impact in between-subject design ones. On the other hand, repulsion hypothesis, in which dissimilar attitude decrease the attraction but similar attitude has no effect on it, has been supported in between-rather than within-subject design studies. These inconsistencies seemed to reflect the fact that the results were more difficult to be significant in betweenthan within-subject designs. Thirty male and eighteen female undergraduates participated in within-subject design experiment (Exp. 1), and three hundred fifteen male and one hundred fifty one female undergraduates did in between-subject design experiment (Exp. 2) to explore the effects of attitude importance, set size, and repulsion on interpersonal attraction. The results suggested that the set size effect was confirmed only in within-subject design and repulsion hypothesis was supported only in between-subject design, while the importance of attitude affected the similarity-attraction relations in both designs. These results imply that the interpersonal attraction can be explained with the common psychological mechanisms to impression formation or decision making.
