Infants' Attributions of Insides and Animacy in Causal Interactions

Past work has found that infants show more interest when an object that has at least two properties of animate beings, such as engaging in self-generated motion and having fur, is shown to be hollow than when an object with none or one of these properties is revealed to be hollow. When an object is grabbed by a hand and moved to a new place, by 7 months of age, infants explain the motion of the object as due to the hand, and thus do not interpret this object as capable of self-generated motion. This constant application of force is called an "entraining" event. Other work has found that 6-month-old infants are sensitive to the reversals of causal roles in "launching" events (billiard-ball-like collisions), but not entraining events. Here, we examine whether 10-month-old infants explain the motion of the patient in a launching event as being due to the contact with the launching agent. Experiment 1 replicates past work, showing that infants look longer when a self-propelled object with animate features (fur or feathers) is shown to be hollow, compared to a similar object undergoing spatiotemporally identical motion entrained by a human agent. Experiment 2 finds that infants look equally at the agent and patient, both covered by fur or feathers, of a launching event when each is revealed to be hollow. Experiment 3 shows that infants look longer when a fur-covered causal patient is shown to be hollow compared to a plain-box causal agent, indicating that 10-month-old infants do not explain the motion of the causal patient of a launching event as due to the agent, even though they do so for an entraining event. This dissociation suggests the existence of multiple independent causal representations in the first year of life.