Age‐related differences in memory expression during infancy: Using eye‐tracking to measure relational memory in 6‐ and 12‐month‐olds

Abstract

Relational memory, or the ability to bind components of an event into a network of linked representations, is a primary function of the hippocampus. Here we extend eye-tracking research showing that infants are capable of forming memories for the relation between arbitrarily paired scenes and faces, by looking at age-related changes in relational memory over the first year of life. Six- and 12-month-old infants were familiarized with pairs of faces and scenes before being tested with arrays of three familiar faces that were presented on a familiar scene. Preferential looking at the face that matches the scene is typically taken as evidence of relational memory. The results showed that while 6-month-old showed very early preferential looking when face/scene pairs were tested immediately, 12-month-old did not exhibit evidence of relational memory either immediately or after a short delay. Theoretical implications for the functional development of the hippocampus and practical implications for the use of eye tracking to measure memory during early life are discussed.

What goes where? Eye tracking reveals spatial relational memory during infancy

“…Using another eye-tracking paradigm in which infants learned about pairs of faces and backgrounds, we showed that infants as young as 6 months will look preferentially at faces that were previously paired with the test background within a few hundred milliseconds of stimulus onset (Richmond & Nelson, 2009;Richmond & Power, 2014). In combination, these data suggest that infants are able to learn about arbitrary stimulus relations as well as the spatial relations much earlier than was previously thought.…”

“…In sum, our work has shown that, much like relational memory for arbitrarily paired stimuli (Richmond & Nelson, 2009;Richmond & Power, 2014), infants encode information about the relative position of objects in the environment much earlier than they are able to use that information to guide search behavior. Eye-tracking methods have much potential to contribute to understanding of relational learning early in life; however, our understanding of how infants come to use relational information to guide flexible behavior continues to be limited by our ability to design paradigms to measure infants' behavior.…”

“…It seems that infants' ability to encode the relative position of objects may develop along a similar time course as their ability to bind together arbitrarily paired stimuli (Richmond & Nelson, 2009;Richmond & Power, 2014). Using another eye-tracking paradigm in which infants learned about pairs of faces and backgrounds, we showed that infants as young as 6 months will look preferentially at faces that were previously paired with the test background within a few hundred milliseconds of stimulus onset (Richmond & Nelson, 2009;Richmond & Power, 2014).…”

“…Consistent with previous work using eye tracking to measure relational memory (Richmond & Nelson, 2009;Richmond & Power, 2014), infants needed to spend at least 2500 ms 1 fixating the stimuli during the test trial and contribute data on both location switch and object switch trials in order to be included in analyses. Areas of interest (top left, top right, and bottom middle) were defined a priori using inline code in the E-Prime script.…”

“…Here we used 10,000-ms test trials; however, most infants spent only half of that time fixating the stimuli (M = 4870 ms, SD = 1824). We acknowledge that the trial length was likely too long, and rather than excluding more than half of the infants, we set the minimum test look criterion to be consistent with our previous work using a similar paradigm (Richmond & Nelson, 2009;Richmond & Power, 2014). ual fixations were then analyzed to determine the percentage of time spent fixating the target positions during the study trials and the percentage of time spent fixating the manipulated positions during test.…”