Sensitive perception of a person's direction of walking by 4-year-old children.

Watch any crowded intersection, and you will see how adept people are at reading the subtle movements of one another. While adults can readily discriminate small differences in the direction of a moving person, it is unclear if this sensitivity is in place early in development. Here, we present evidence that 4-year-old children are sensitive to small differences in a person's direction of walking (∼7°) far beyond what has been previously shown. This sensitivity only occurred for perception of an upright walker, consistent with the recruitment of high-level visual areas. Even at 4 years of age, children's sensitivity approached that of adults'. This suggests that the sophisticated mechanisms adults use to perceive a person's direction of movement are in place and developing early in childhood. Although the neural mechanisms for perceiving biological motion develop slowly, they are refined enough by age 4 to support subtle perceptual judgments of heading. These judgments may be useful for predicting a person's future location or even their intentions and goals.