Three experiments (total N = 140) tested the hypothesis that 5-year-old children's membership in randomly assigned "minimal" groups would be sufficient to induce intergroup bias. Children were randomly assigned to groups and engaged in tasks involving judgments of unfamiliar in-group or out-group children. Despite an absence of information…

This study compared 2- to 4-year-olds who understand how counting works ("cardinal-principle-knowers") to those who do not ("subset-knowers"), in order to better characterize the knowledge itself. New results are that (1) Many children answer the question "how many" with the last word used in counting, despite not understanding how counting works;…

The present study investigated the development of possibility-judgment strategies between the ages of 4 and 8. In Experiment 1, 48 children and 16 adults were asked whether a variety of extraordinary events could or could not occur in real life. Although children of all ages denied the possibility of events that adults also judged impossible,…

Preverbal infants can represent the causal structure of events, including distinguishing the agentive and receptive roles and categorizing entities according to stable causal dispositions. This study investigated how infants combine these 2 kinds of causal inference. In Experiments 1 and 2, 9.5-month-olds used the position of a human hand or a…

The project of comparative cognition benefits from common measures across species. We report here on five experiments using the violation of expectancy looking time measure with free-ranging rhesus macaques ("Macaca mulatta"), each designed to build on current knowledge concerning spontaneous representations of number. Each subject, tested in only…

Advocates of the ''continuity hypothesis'' have argued that innate non-verbal counting principles guide the acquisition of the verbal count list (Gelman & Gallistel, 1978). Some studies have supported this hypothesis, but others have suggested that the counting principles must be constructed anew by each child. Defenders of the continuity…