Arrows of time in early childhood.

Three studies with 149 children were conducted to provide information about development of the perception of temporally unidirectional transformations, such as dropping blocks or breaking a cookie. Children 3.5 through 6.5 years of age compared forward and backward videotapes of events or made individual judgments of what would happen if the actions were attempted. Even children 3.5 to 4.5 years of age recognized the anomaly of backward versions of gravity and separation events. In addition, relatively few children predicted impossible transformations in the prediction task. The results show that young children, like adults, are sensitive to the unidirectional nature of varied transformations.