"This finding shows not only that one-year-old infants are paying attention to the actions of others, but that they can focus on a behavior in one scene and use that information to interpret behavior in a different scene," said Valerie Kuhlmeier, a postdoctoral fellow in the Department of Psychology and lead author of the study published in the September issue of Psychological Science.
The researchers studied the age at which children begin to interpret the behavior of other individuals based on inferences about other persons' emotions, desires and beliefs. The ability to predict and understand certain mental states is thought to emerge between the ages of three and five years, but there is growing interest in infants' reasoning about the behavior of others.
In this study the infants sat in high chairs and watched two seven-second computer-animated movies. In the first, a square shape helped push a ball up a hill; in the second, a triangle hindered the ball from moving up the hill. Test movies showed the ball approaching the "helpful" square, and then approaching the "not-so-helpful" triangle. Researchers monitored the infants' eye movements.
"The 12-month-old infants looked longer at the ball approaching the helper than the ball approaching the hinderer, which means they differentiated between the movies," Kuhlmeier said. "We believe this was because they had ideas about what type of action would be more likely for the ball given its previous interactions."
Adults shown the same movies saw the ball approaching the helper square as a coherent continuation of the first movie, but did not see the same connection when the ball approached the triangle. Five-month-old infants did not make any distinctions.
Co-authors included Karen Wynn and Paul Bloom, both psychology professors at Yale. The study was supported by a National Institute of Mental Health grant.
Citation: Psychological Science, Vol. 14: 402-408 (September 2003)