Reasoning and relatedness

The purpose of this study was to test for an effect of biological relatedness on reasoning in a Wason card selection task. The behavior of children in a day care was described in a cheater detection rule, an altruism detection rule and a hazard detection rule. Two groups of parents were tested: those who were related and those who were unrelated to the child who was described in the rule. Altruism detection was performed at a lower success rate than cheater detection. As predicted on the basis of inclusive fitness theory, an interaction between problem type (cheater or non-cheater) and relatedness was obtained: an overall superior performance of related parents vanished for the cheater detection problem. Hazard detection was significantly higher for parents related to the child. Parents seem to reason less well about safety rules as they apply to unrelated children compared to rules that apply to their own.