Memory grows up in 1-year-olds

The second year of life may be particularly memorable. Around the time of their first birthday, children make dramatic advances in remembering simple events for 4 months after witnessing them, a new study finds. This memory breakthrough depends on a proliferation of neural connections in memory-related brain structures known to develop as infants approach age 1, propose Harvard University psychologists Conor Liston and Jerome Kagan.

The researchers recruited 12 babies and toddlers at each of three ages: 9 months,

17 months, and 24 months. Children watched an experimenter both perform and describe three action sequences. In one sequence, for example, the experimenter said “Clean-up time!” while wiping a table with a paper towel and then throwing the towel into a trash basket.

Kids in the two older groups watched four demonstrations of each action sequence, and 9-month-olds saw six repetitions. After each presentation, the experimenter encouraged children to imitate what they had just seen.

Four months later, the youngsters–then ages 13 months, 21 months, and 28 months–were asked to reenact each set of actions with the same materials after hearing the same verbal descriptions.

The children now 28 months old correctly performed a majority of previously observed actions, usually in their original order, Liston and Kagan report in the Oct. 31 Nature. The 21-month-olds reenacted what they had seen almost as well as their older peers did. Far fewer signs of accurate recall appeared in 13-month-olds, the only participants who had been under 1 year of age during initial memory trials.

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