Dual process theories postulate the existence of two levels of processing, Type 1, which uses belief-based cues to make very rapid inferences, and Type 2, which uses more conscious, working memory-based processes that are, in principle, capable of making rulebased judgments. There is a common assumption that Type 1 processes are more rapidly produced, while Type 2 processes take more time. Evidence for this assumption is mixed.

The dual-strategy model of reasoning suggests that when people reason they can either use (a) a statistical strategy which generates an estimation of conclusion likelihood using a rapid form of associative processing or (b) a counterexample strategy which identifies potential counterexamples to a conclusion using a more conscious working memory intensive process. Previous results suggest that strategy use is a strong individual difference that represents a broad distinction in the way that information is processed that goes beyond deductive reasoning. In 3 studies, we examined if this model could predict individual differences in the processing of social information by examining socially relevant cognitive biases. Study 1 found that strategy use predicted the extent of the self-serving bias. Study 2 found that strategy use predicted use of racist stereotypes even when need for closure was accounted for. Study 3 found that an essentialist prime resulted in a higher level of gender bias among statistical reasoners but that this prime had no effect on counterexample reasoners. These results indicate that the processing distinction between the 2 reasoning strategies underlies individual differences in social biases such as stereotypes, sexism, and racism.

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This study explored the hypothesis that preschoolers’ deductive reasoning would be improved by encouraging use of divergent thinking (DT). Children of 4–5 years of age (n = 120) were randomly given DT or neutral control exercises before deductive reasoning problems. To allow a stronger test of the hypothesis, half of the children receiving the DT exercises were given explicit examples, which have been shown to reduce ideational originality. Results indicate that, as predicted, DT exercises without examples significantly improved rates of deductive responding, compared to exercises with examples and the control condition. These findings indicate that DT is a key component in the early beginnings of deductive reasoning. Some educational implications are discussed.

Studies on human cooperation using economic games rarely include ecologically relevant factors. In studies on non-human primates however, both status and sex typically influence patterns of cooperation. Across primate species, high status individuals are more likely to cooperate, though this depends on the species-specific social structure of each sex. Based on human social structure, we predict that higher status males who interact more in hierarchical groups than females, will invest more than high status females in valued same-sex peers after successful cooperation. Across three studies, 187 male and 188 female participants cooperated with a (fictitious) same-sex partner who varied in competence. Participants then divided a reward between themselves and their partner. High status was induced in three different ways in each study, social influence, leadership and power. No overall sex difference in reward sharing was observed. Consistent with the hypothesis however, across all three studies, high status males invested more than high status females in cooperative partners, suggesting that high status males intuitively evaluate sharing rewards with same-sex partners as more beneficial.