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即使是非常年幼的孩子也會回想過去的事情

By Salynn Boyles
WebMD Health News

Reviewed by Laura J. Martin, MD

May 11, 2011 -- New research challenges the notion that very young children do not form memories, finding that they do but that the memories often fade over time.

Most adults remember little before their third or fourth birthdays, and the thinking has been that prior to this age children do not have the cognitive or language skills to process and store events as memories.

But psychology professor Carole Peterson, PhD, and colleagues from Canada's Memorial University of Newfoundland confirmed in earlier research that this is not the case and that even very young children can recall past events.

Now they report that young children's earliest memories tend to change over time, being replaced with "newer" earliest memories until around age 10. As this happens, memories occurring in the preschool years tend to be lost.

"As young children get older their first memories tend to get later and later, but around age 10 their memories crystallize," Peterson tells WebMD.

Checking Children's Memories

In an effort to better understand how children form memories, the researchers asked 140 kids between the ages of 4 and 13 to describe their earliest memories and then asked them to do the same thing two years later.

On both occasions, the children were also asked to estimate their age at the time of each memory, and parents were questioned to confirm that the events happened.

The researchers found that children between the ages of 4 and 7 during the first interview showed very little overlap between the memories they recalled as "first memories" during the first question session and those they remembered two years later.

"Even when we repeated what they had told us two years before, many of the younger children would tell us that it didn't happen to them," Peterson says.

Conversely, a third of the children who were age 10 to 13 during the first interview described the same earliest memory during the second interview. More than half of the memories they recalled were the same at both interviews.

The researchers are now studying why children remember certain events and not others.

Peterson says traumatic or highly stressful events made up only a small percentage of the earliest memories reported by children in the study.

Cultural Differences Influence Early Memory

Earlier research suggests that culture plays a big part in early memory.

When Peterson and colleagues compared early memories in groups of Canadian and Chinese children, they found that the Chinese children's earliest memories tended to be a year or more later than the earliest memories of Canadian children.

Emory University child memory researcher Robyn Fivush, PhD, found the same thing in a study comparing Chinese and American children.

Fivush tells WebMD that Western children tend to have stronger early memories because their dialog with parents and other adults tends to be more autobiographical.

"As we know from watching Oprah and Dr. Phil it is perfectly OK to talk about yourself in this culture. But in China it is less appropriate to talk about yourself or call attention to yourself," Fivush says. "It is more appropriate to talk about events in the context of the group."

She cites studies finding that children who are asked a lot of questions about their personal experiences and feelings by their mothers tend to develop memory skills earlier. Since dialog among Chinese mothers and their children tends to be less child-centered, memory may develop later.

"In return Chinese children tend to develop other skills, such as a better ability to pay attention," she says. "Of course there are huge individual differences within cultures in how mothers relate to their children."

SOURCES: Peterson, C. Child Development, online, May 11, 2011.Carole Peterson, PhD, professor of psychology, Memorial University of Newfoundland, Newfoundland, Canada.Robyn Fivush, PhD, professor of psychology, Emory University, Atlanta.News release, Society for Research in Child Development.Fivush, R. Child Development, 2006; vol 77: pp 1568-1588.Wang, Q. Social Cognition, 2006; vol 25: pp 455-471. ©2011 WebMD, LLC. All Rights Reserved

 加拿大的研究發現，非常年幼的孩子也會有記憶，但常會在一段時間後淡忘。