Jerome Kagan
Jerome Kagan describes areas at the front of – and deep within – the brain which must mature and plant connections earlier long-term memory is firmly established. (Staff photo past Jon Hunt)

It'south been known for a while that babies savour a dramatic increase in their power to remember people and things between eight and 12 months of historic period. Simply this is brusk-term memory, the kind that loses a telephone number in a minute or less if you don't write information technology down.

Long-term memory is something else. Most people recall where they were on the morning time of Sept. 11, 2001. Only when do humans develop this ability to retrieve something for well-nigh if non all of their lives?

Information technology was a natural question for Conor Liston, a Harvard senior, and his mentor Jerome Kagan, Starch Research Professor of Psychology. Liston conducted experiments under Kagan'south supervision, and they came up with an respond.

"Our findings advise that children have great difficulty recalling the by earlier the stop of the first year of life," says Kagan.

Liston introduced 3 groups of children, 9, 17, and 24 months old, to a serial of distinctive experiences. These included making a rattle by putting a plastic band through a slot and into a bottle, so shaking the bottle. Four months later, he revisited the same kids and gave them the same toys. For the most part, the 9-calendar month-olds, at present thirteen months of age, didn't call back what to do with toys. The 17- and 24-month-olds, now 21-28 months former, nonetheless, showed robust memories of what they had seen and done with the objects.

"Nosotros translate this to mean that, at nine months, the human brain is too young to firmly register experiences, while at 17-21 months it has developed enough to record and retrieve memories of single distinctive experiences," Kagan says.

Does this mean that infants younger than eight months to a year old don't acquire anything from mom and dad'due south reading, playing with them, singing to them, and so on? "Almost unmarried experiences earlier historic period 8 months, unless they are very emotional or painful, are probably lost," Kagan replies. "Yet, in that location are important reasons for pursuing such activities. They go along kids alert and aroused. Many studies show that children who experience lots of attention and diversity are intellectually better off than those who are isolated or ignored. Variety and attention are food that makes young minds grow."

Filling a bare slate

Non as well long ago, in the 1940 and '50s, most psychologists believed that a newborn's heed was a blank slate. Every bit a child manipulates things and sees the outcome, those experiences make full the slate with scribbles that become long-term memories. "This popular point of view held that y'all can teach any child anything," Kagan comments. "That was optimistic, egalitarian, liberal, extreme, and wrong."

Since and so, battalions of neuroscientists, conducting experiments with humans and animals, have clustered information to prove that, after nascency, the brain is still growing. In fact, at nativity the brains of horses and goats are more than mature than those of humans.

In subsequent months, cells in the frontal lobe of the brain and in the hippocampus, two regions necessary for long-term memories to form, undergo a spurt of growth. The hippocampus, a pocket-size S-shaped surface area deep in the encephalon, sends long extensions of its nerve cells to the front end of the brain, and cells in the frontal cortex reach out to the hippocampus. "These circuits must be mature before long-term memories can be recorded and retrieved," Kagan maintains.

Conor Liston wanted to know when this happens. Various researchers had tested the memories of children a calendar month or and then after exposing them to a memorable experience, just no one had checked their recall after longer delays.

Liston went to Kagan for assist to practise the necessary experiments. The Provost's Role at Harvard gives grants to conduct such inquiry under two programs, one called the Children's Initiative, the other the Listen/Brain/Behavior Initiative. These grants are named in honor of Kagan. Liston, appropriately, won a Kagan Accolade.

Using mass mailings, Liston recruited 12 9-calendar month-olds and an equal number of 17- and 24-month-olds from eye-class families in Boston. He went to their homes and demonstrated different games to the kids. For case, in "Load the Truck," he put a toy driver in the driver's seat of a toy truck, put a small rock in the truck bed, then rolled the truck.

Liston repeated the sequences several times, then encouraged the children to imitate what was done. He did this for three separate games. So he went away and came back four months later on.

Who tin play the game

At these after sessions, the games were non demonstrated to the youngsters, but they were encouraged to play them by themselves. Each child was challenged past three games she or he had played earlier and two novel games.

The at present thirteen-month-olds behaved as if they had never played such games before. They did as poorly on the familiar games as they did on the novel ones. The 21- and 28-calendar month-olds, in contrast, showed a strong recollection for the games they had played. They performed significantly better on the familiar sequences than on the novel ones.

Liston also tested children who had never played any of the games, every bit a means of making certain that the sequences were not something babies might pick up naturally. The 21- and 28-month-old controls showed no skills at playing any of the games, every bit expected.

"We suggest that this retention enhancement, or lack of information technology, is due to brain development between age ix and 17 months," Kagan says of the results, published in the Oct. 31 issue of the scientific journal Nature.

Kagan sees i applied application for the inquiry. Many families in the Us are adopting babies, specially from other countries. New parents frequently worry almost whether the adoptees will have problems adjusting to new homes and cultures. "If the babies are younger than viii months, odds are they accept no lasting memories of what happened to them," Kagan points out. "Their transition will be less confusing and bonding much easier than for children older than 1 yr."