A new quantitative model of interpersonal attraction was proposed. This model predicts the contradictory results to Byrne's reinforcement model in the effect of topic importance of attitude on the relations between similarity and interpersonal attraction. Seventy three male and nine female undergraduate students in Exp. 1 were prenented with two strangers' attitudes simultaneously and rated the attraction of them. Ninty seven male and twenty one female undergraduates in Exp. 2 were also presented with two stranger's attitudes successively and evaluated their attraction first, then reevaluated them with the information that they were the same person. The results suggest that the attraction is more polarized for strangers of important rather than unimportant attitude when the importance of attitude is within subject factor. Implications are discussed in terms of the quantitative models of attraction, such as information integration and expectancy value models.
