Young infants' expectations about a self-propelled agent's body.

What intuitive biological understandings do infants have? Recent work reports that 8-month-olds seem to identify self-propelled agents as animals and expect them to have a closed body. The present study examined a group of 6.5-month-old infants' (N = 50, 52% female, 84% White) biological expectations. The infants seemed to grasp the causal link between a novel self-propelled box agent's functioning and its body because they expected a temporary operation (i.e., an experimenter opening the box, exposing its insides, and closing it) to impair its ability to move. Further, infants accepted what was shown inside the box during the operation; whether it had an internal cuboid did not affect the results. Together, this suggests that infants at this young age appear to recognize the importance of having an intact body to a novel self-propelled agent's mobility but have no specific knowledge about what should be inside such an entity. These findings thus shed new light on the developmental origins of biological understandings.