Infants' Insight into the Mind: How Deep?

Understanding that others may act based on false beliefs is considered a uniquely human ability. Children are thought to develop an understanding of false beliefs around 4 years of age, which implicates a tie to a cultural process involving language. However, as Perner and Ruffman discuss in their Perspective, a new study (Onishi and Baillargeon) suggests that infants as young as 15 months may have insight into whether a person acts on the basis of a mistaken view (false belief) about the world. Perner and Ruffman argue that the behavior of 15-month olds in this study does not mean that they necessarily understand belief.