Children as young as three already have a sense of how well they
can remember things, but metamemory keeps on developing throughout
childhood. With their undiscriminating "Cookie-Monster" minds, toddlers
gobble up all the information they encounter. They just can't organize or
monitor this wealth.
If your three-year-old nephew remembers your wristwatch or your car
better than your face, it's because the details of your last visit are
jammed higgledly-piggeldy into a disorganized memory. It's easier for the
child to call up some items, impossible to retrieve others, because his
metamemory isn't sufficiently developed to organize the data in his
mind.
"You could say metamemory is a byproduct of going to school," says
psychologist Robert Kail, Ph.D., of Purdue University, who studies
children from birth to 20 years, the time of life when mental development
is most rapid. "The question-and-answer process, especially exam-taking,
helps children learn--and also teaches them how their memory works This
may be one reason why, according to a broad range of studies in people
over 60, the better--educated a person is, the more likely they are to
perform better in life and on psychological tests.
A group of adult novice chess players were compared with a group of
child experts at the game. In tests of their ability to remember a random
series of numbers, the adults, as expected, outscored the children. But
when asked to remember the patterns of chess pieces arranged on a board,
the children won. "Because they'd played a lot of chess, their knowledge
of chess was better organized than that of the adults, and their existing
knowledge of chess served as a framework for new memory," explains
Kail.
Things may be different, however, with different types of
cognition. At the University of Oregon, Michael I. Posner, Ph.D., deploys
brain-imaging techniques to map the neural networks involved in the task
of paying attention. He has found that the neurotransmitter
norepinephrine is involved in the alerting function that allows us to
focus attention on one object, and in the inhibitory mechanism that helps
us screen out irrelevant stimuli. Age-related failures in this system, he
thinks, might account for the way older people are easily distracted and
tend to ramble on in conversation. "Attentional systems, like any mental
activity that involves speed and Puts stress on the system, show a big
decline over age 70," he reports.
Georgia Tech's Timothy Salthouse detects age-related disparities in
certain kinds of reasoning functions, such as spatial ability. Subjects
are shown a pattern and then asked to turn it mentally and view it from
another angle. "If we give the same fairly simple cognitive tests to 30
or 40 people in their 20s and to others in their 40s, we can spot some
clear differences," Salthouse says.
Cross-sectional studies of this kind dominate the literature;
recruiting and studying at one time lots of people of different ages is
simpler and cheaper than following individuals throughout life and
testing them periodically. Cross-sectional studies assume that today's
60-year-old is what today's 40-year-old will be like 20 years from now.
But even Salthouse, who conducts such studies, warns such an assumption
can be wrong.
"Test-score differences between age groups aren't necessarily
caused by inevitable, irreversible biological changes," muses Salthouse.
The world is changing under our feet, it seems. "There's more cultural
stimulation nowadays, which might give an advantage to people who grew up
with television, Head Start programs, and other influences that weren't
around earlier."
Still, he thinks that the available evidence supports the inference
that any differences between college students and older people more or
less reflect the changes that go on in individuals, and that downward
changes really do begin as early as the 20s.
Using different methods, psychologist Warner Schaie, Ph.D., has
detected no differences in various kinds of cognition until age 60.
"After that, we find great individual differences over the next 20 years,
with some people going downhill dramatically and others doing as well as
ever."
Schaie logs nearly 40 years of longitudinal research that began
with his doctoral dissertation. A few of his first subjects continue to
return every seven years for tests that monitor their verbal, numeric,
and spatial reasoning, perceptual speed, various kinds of memory, and
other mental abilities. His test population comes from a large Seattle
HMO.
The 1991-1992 wave of testing, yielding data on over 1,000 people,
included 75 of the original subjects returning for their sixth round of
tests. All told, there's data on about 5,000 people. The study is
virtually unique in its size and duration, and even researchers who
disagree with some of Schaie's conclusions are quick to concede that
their data aren't nearly as solid.
The research indicates strongly that the period between ages 50 and
60 is diagnostic-people in their 50s who show signs of fading won't do
well mentally in later years, when it's virtually impossible to structure
a new set of mental habits. After 50, mental function is largely
determined by three factors--the mental lifestyle, the impact of chronic
disease, and the flexibility of the mind.
THE BIG THREE
Tags:
academic title,
aging,
arnold b scheibel,
baby boom,
behavioral sciences,
brain,
brain research institute,
cell biology,
chimps,
continuous interaction,
conventional wisdom,
experimental evidence,
lower animals,
maturation process,
Memory,
memory tests,
mental function,
mental functions,
mileposts,
mind,
petty pace,
population bulge,
power of the mind,
university of california at los angeles
