Study Finds Jump in Infant Memory in 2nd Year

A Harvard-led study has shown that infant memory vastly improves during the second year of life, and researchers speculate that the improvement is related to brain development during this time.

The study, led by Conor M. Liston ’02, was published in last week’s issue of the journal Nature. Liston ran experiments that tested a child’s ability to reenact novel but easily imitated actions.

The subjects—9-, 17-, and 24-month-old infants—witnessed a multi-step task, such as placing a towel in a trash can, and were asked to imitate it after hearing a verbal cue.

Four months later, researchers brought the subjects back and asked them to repeat the tasks on verbal cue—this time without a demonstration.

According to the study, only 11 percent of 13-month-old toddlers successfully repeated at least one of the multi-step tasks they performed as nine-month -olds.

But 91 percent of the 21-month-olds were able to repeat at least one of the tasks they had imitated four months earlier.

All of the 28-month-old replicated at least one of the tasks they performed at 24 months, according to the study.

The results reinforce the idea that memory improvement during infancy is directly related to the development of the brain’s frontal lobe and hippocampus—parts of the brain responsible for memory retention and retrieval.

Researchers have concluded that year-old toddlers are forgetful because certain parts of their brain are still developing.

Starch Research Professor of Psychology Jerome Kagan, who aided Liston in his research, said that the study is significant because it provides empirical data linking memory improvement with a specific year of development.

While prior research has been done to show that memory does increase during the second year of life, this experiment is the first to take four months between testing a child’s recollection of the task, Kagan said.

The next step, according to Professor of Psychology Susan E. Carey, is to formulate a hypothesis as to why these changes occur. Changes other than brain development, such as better verbal skills and self-awareness, could also be responsible for memory improvement.

“An increase in memory could also be caused by a developing understanding and the child’s place in it,” Carey said. “There is a developing sense of self and a great language development.”