- The Washington Times - Thursday, October 31, 2002

ASSOCIATED PRESS

Scientists have confirmed what many mothers know: A 1-year-old child's absent-mindedness is replaced with robust memory-recall in the second year of life.

The researchers said their findings add weight to the theory that year-old toddlers are forgetful because the regions of their brains that store and retrieve long-term memories are still forming.

Other scientists said while the new work confirms earlier research that toddlers' memories improve with age, it remains unclear what prompts the improvements.

Harvard University researchers tested three different age groups of toddlers by encouraging them to imitate multistep tasks such as wiping a table clean and placing a paper towel in a trash can.

As they were spurred to imitate each task, the children were goaded along with verbal cues, such as, “Cleanup time.”

Four months later, researchers used the same verbal cues and props to determine whether the children could re-enact the tasks. They found that only 11 percent of 13-month-old toddlers successfully repeated at least one of the multistep tasks they performed as 9-month-olds.

But 91 percent of the 21-month-olds were able to repeat at least one of the tasks they imitated at 17 months, and all of the 28-month-olds replicated at least one of the tasks they performed at 24 months.

The research appears in today's issue of the journal Nature.

Conor Liston, who led the Harvard study, said the research confirms and adds to findings published in the mid-1990s by researchers from the University of Washington and the University of Minnesota.

Mr. Liston said his work is among the first to compare the long-term memory-recall abilities of 9-month-olds with those of 17-month-olds.

Previously, University of Washington research showed that 6-month-old babies can remember events for only about 24 hours, while scientists at the University of Minnesota found that the life span of toddlers' memories improves to up to a month by the time they are 9 months old.

“This indicates pretty strongly that there are some developments occurring in the brain between nine months and 17 months that enable the older children to encode memories at 17 months that can be recalled after a long period of time,” said Mr. Liston, who was aided in his research by Jerome Kagan, a Harvard professor of psychology.

Lise Eliot, an assistant professor of neuroscience at the Chicago Medical School, notes that the Harvard study did not look at changes in the test subjects' brains.

Still, she agrees that the findings add to the idea that the development of the brain's frontal lobe and hippocampus areas tied to memory retention and retrieval are key to the dramatic improvement in toddlers' memory-recall in their second year.

“It's a gradual process. It's not like the hippocampus is off and it suddenly turns on. It gradually works its way up to full speed,” she said.

Alison Gopnik, a professor of psychology at the University of California at Berkeley, said it is speculative to attribute the memory improvement in the second year solely to the brain's development.

She said a child's experiences, growing verbal skills and self-awareness may well play a role in sharpening memory and that those changes could lead to changes in the brain.

“You would have to do some very different kinds of studies to try and show that it was the brain's maturation leading to the change, and not changes in experience leading to brain changes,” she said.

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