Look who's Remembering

Do you remember when you were six months old, and your family took a trip to Disneyland? The latest research in infant long-term memory development suggests no, you wouldn’t, because your young brain was not sufficiently developed to form the long-term memory that would allow you to remember that event.

This new study, conducted by Conor Liston, a senior student at Harvard, under the supervision of Jerome Kagan, a professor of psychology and director of the Mind-Brain-Behavior Initiative, involved 36 infants, 12 in each of three age groups: nine months, seventeen months and twenty-four months. The infants were shown a motion, such as putting a ring into a bottle and shaking it, or wiping a table with paper towel, while being given verbal cues “make a rattle” and “clean-up time.” The infants were shown the task multiple times and given the opportunity to duplicate the action.

At the follow-up four months later, the children, now aged 13, 21 and 28 months were given the same props from the earlier experiments and the verbal cue, as well as two new exercises. The 21 and 28 month-olds recalled the appropriate actions, however the youngest group did not know what to do. Both groups performed poorly on the new activities.

Liston’s conclusions were published in British science journal Nature in October 2002. “Regions of the brain's frontal lobe that are associated with memory retention and retrieval begin to mature during the last quarter of the first year in humans. This implies that infants younger than 8 or 9 months should have difficulty in registering an experience and retrieving it after a long delay . . . Our findings indicate that long-term retention increases during the second year and support the idea that maturation of the frontal lobe at the end of the first year contributes to memory enhancement during this period.”

Throughout the first year of an infant’s life, the child will demonstrate limited short-term memory, however long-term memory is almost non-existent. A six-month-old, for example, may remember an experience from the year before. Towards the end of the child’s first year, neurons begin to grow rapidly in the neocortex. Located in the frontal lobe, the neocortex has been shown to be used by adults in recollection. As neural growth explodes, the capacity for long-term memory retention increases, and thus infants are able to remember activities that have taken place four months earlier.