Relational memory during infancy: evidence from eye tracking.

Here we report evidence from a new eye-tracking measure of relational memory that suggests that 9-month-old infants can encode memories in terms of the relations among items, a function putatively subserved by the hippocampus. Infants learned about the association between faces that were superimposed on unique scenic backgrounds. During test trials, infants were shown three faces presented on a familiar scene. All three faces were equally familiar; however, one had been presented with the test background earlier. Visual behavior was recorded continuously using a TOBII eye tracker. Infants looked preferentially at the face that matched the test background very early in the trial; however, the time course of this preferential looking effect varied as a function of delay. These results suggest that by 9 months of age infants can form memories that represent the relations among items and maintain them over short delays.