Jeffrey L. Kirchner

Is actual similarity necessary for attraction? A meta-analysis of actual and perceived similarity:

To evaluate the impact of actual and perceived similarity on interpersonal attraction, we meta-analyzed 460 effect sizes from 313 laboratory and field investigations. Results indicated that the associations between interpersonal attraction and both actual similarity (r = .47) and perceived similarity (r = .39) were significant and large. The data also indicate that (i) actual similarity was important in no-interaction and short-interaction studies, (ii) there was a significant reduction in the effect size of actual similarity beyond no-interaction studies, and (iii) the effect of actual similarity in existing relationships was not significant. Alternatively, perceived similarity predicted attraction in no-interaction, short-interaction, and existing relationship studies. The implications of perceived similarity, rather than actual similarity, being predictive of attraction in existing relationships are discussed.

Interindividual-Intergroup Discontinuity as a Function of Trust and Categorization: The Paradox of Expected Cooperation

Two experiments used a 3-choice variation of the prisoners dilemma game to explore the paradoxical implications of expected cooperation of other groups and individuals for competitiveness and cooperativeness. Experiment 1 found that an experimental manipulation of opponent trustworthiness influenced the tendency of both groups and individuals to cooperate but had no significant effect on the tendency of groups and individuals to compete--possibly because of the perceived unfairness of competing with a trustworthy other. Experiment 2 found that an experimental manipulation of categorization increased the tendency of same-category groups and individuals to cooperate (as in Experiment 1) and also increased the tendency of same-category groups, but not individuals, to compete (unlike in Experiment 1). It was further found that the tendency of same-category groups to compete more than same-category individuals was relatively stronger for participants high in guilt proneness.

Reduction of interindividual-intergroup discontinuity: the role of leader accountability and proneness to guilt.

Two experiments contrasted interactions between group leaders with interactions between individuals in a mixed-motive setting. Consistent with the idea that being accountable to the in-group implies normative pressure to benefit the in-group, Experiment 1 found that accountable leaders were more competitive than individuals. Consistent with the idea that being unaccountable to the in-group implies normative pressure to be cooperative and that high guilt proneness provides motivation to be moral, Experiment 2 found that when guilt proneness was high, unaccountable leaders were less competitive than accountable leaders and did not differ significantly from individuals. In other words, the robust interindividual-intergroup discontinuity effect was eliminated when groups had unaccountable leaders who were high in guilt proneness.

Interindividual-intergroup discontinuity in the domain of correspondent outcomes: the roles of relativistic concern, perceived categorization, and the doctrine of mutual assured destruction.

Most prior research on the tendency for groups to be less cooperative than individuals (the interindividual-intergroup discontinuity effect) has used the Prisoners Dilemma Game (PDG). Experiment 1 examined the discontinuity effect with 3 additional matrices: Chicken, Leader, and Battle of the Sexes (BOS). Unlike the PDG, these matrices are characterized by correspondence of outcomes. The discontinuity effect was significant for the PDG and Chicken matrices only. With the BOS and Leader matrices, both individuals and groups pursued outcome maximization through coordinated turn taking. Despite the lesser competitiveness, sets of interacting participants in the BOS and Leader conditions did perceive that they were 2 groups. Experiment 2 examined the discontinuity effect in 2 Chicken matrices with varying outcomes associated with mutual competition. Consistent with the doctrine of mutual assured destruction, the discontinuity effect was eliminated for the matrix in which mutual competition was associated with very low outcomes. Although concern for relative in-group standing gave rise to intergroup competition even in the domain of correspondent outcomes, such concern was constrained to the extent that it interfered with outcome maximization.