How do 8-month-old infants recognize causality in object motion and that in human action?

Abstract

In Experiment 1, 8-month-old infants were first habituated to the event in which a moving object collided with another behind an occluder, then they were shown the two test events with no occluder: the contact event, in which the two objects actually collided, and the non-contact event, in which the second object started to move without contact with the first. The infants looked at both events for an equal amount of time. In Experiment 2, in which the first object was a human actor, however, infants looked at the non-contact event reliably longer than the contact event. In Experiment 3, in which both objects were human actors stood face-to-back, infants looked at the non-contact event longer, whereas in Experiment 4, in which human actors faced toward each other, infants looked at both events equally. In Experiment 5, in which the first actor told the second to go, 10-month-old infants looked at both events for an equal amount of time. These results suggest that 8- and 10-month-old infants appreciate different causal principles between objects and humans, and that, in doing this, they may acknowledge the possibility of communication between humans.