Who is the dynamic duo? How infants learn about the identity of objects in a causal chain

Four experiments investigated infants' and adults' knowledge of the identity of objects in a causal sequence of events. In Experiments 1 and 2, 18- and 22-month-olds in the visual habituation procedure were shown a 3-step causal chain event in which the relation between an object's part (dynamic or static) and its causal role was either consistent or inconsistent with the real-world. In Experiment 3, 22-month-olds were tested with a delayed launching causal chain in which the second object, rather than the first, was the agent of the outcome. In Experiment 4, adults were shown the same events and were asked to judge whether the first or second object in the causal chain was animate or inanimate. Experiments 1 and 2 revealed that 18-month-olds were unconstrained in the part-causal role relations they would encode, but 22-month-olds learned only those relations that were consistent with the real-world. Experiment 3 showed that 22-month-olds expect the second object in a delayed launching sequence to possess a dynamic, moving part. Experiment 4 showed that adults expect the first object of a causal chain to be animate and the second object to be inanimate. The results are discussed with regard to the developmental timetable for causal learning and the mechanisms for early concept acquisition.