Big thinkers | Harvard Gazette

[Lotte] Thomsen and colleagues at Harvard and the University of California, Los Angeles (UCLA), studied the reactions of infants ranging from 8 to 16 months old as they watched videos of interactions between cartoon figures of various sizes.

“Since preverbal infants can’t be interviewed, their experiences and expectations must be assessed by their behavior,” Thomsen says. “Infants tend to watch longer when something surprises them. So we can test hypotheses about what they expect by measuring how long they look at scenarios that either violate or confirm their expectations.”

The researchers showed infants videos depicting a large and a small block with eyes and mouth bouncing across a stage in opposite directions. Next, infants watched the two blocks meet in the middle, impeding one another’s progress. They then saw either the large or the small block bow and step aside, deferring to the other.

“As predicted by our theory, the infants watched much longer when a large agent yielded to a smaller one,” Thomsen says. On average, the babies watched this unexpected outcome for 20 seconds, compared with just 12 seconds when a smaller character made way for a larger one.

In a follow-up experiment, Thomsen and her co-authors found that 8-month-old infants failed to grasp the significance of the larger block deferring to the smaller one. But those who were 10 to 16 months old consistently demonstrated surprise at depictions of a larger individual yielding to a smaller one, suggesting that this conceptual understanding develops between 8 and 10 months of age.

Two other follow-ups showed that infants’ reactions were not simply caused by the expectation that smaller individuals tend to fall over in general, including in situations that do not involve conflicting goals.