Cognitive rationality is heritable and lies under general cognitive ability

Intelligence and rationality both predict optimal decision making. However, whether cognitive rationality (CR) and general cognitive ability (CA) are identical or reflect fundamentally distinct processes is hotly debated. Here, we report a twin study aimed at distinguishing the cognitive mechanisms involved in CR and CA. CR and CA tests were administered to a large twin sample. Univariate analyses indicated that both CA and CR were strongly heritable. Multivariate modelling of CA scales and CR indicated that CR was accounted for by a latent g -factor, which itself was strongly heritable. We conclude that CR is not a distinct disposition from CA, but instead that the reflexive and reflective aspects of cognitive ability make making CR a robust and efficient test of general cognitive ability. • Cognitive rationality (CR) claimed to tap “ cognitive miserliness ”. • Large twin study of genetics of CR and cognitive ability (CA). • CA and CR both highly heritable. • CR lies genetically under CA hierarchy. • CR efficiently measures cognitive ability.