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MORE ABOUT FINDING AND STUDIES ON AGING AND IQ
The finding about aging and IQ has been demonstrated repeatedly: people who have a complex life-style, who have compelling interests, activities, and - just as important - meaningful, stimulating contact with other people tend, if anything, to increase their scores on the first part of the IQ test. When crystallized intelligence does decline after age fifty, or seventy, it is often because our lives have become less stimulating - through illness, or lack of opportunity, or losing interest in learning new things.
Unfortunately, the findings are not so upbeat for fluid intelligence. This type of intelligence does begin to decline rapidly and quite early, by our late twenties or early thirties. The main reason is loss of speed. As we get older we get slower, not so much in how fast we move, but in how fast we think. The gradual loss in fluid intelligence begins right after we reach adulthood. But it only becomes a real problem in some limited situations by about midlife.
For instance, an air-traffic controller may notice his performance at work getting worse by his early forties. His job depends on split-second decisions, and so his skill is likely to be affected a good deal by age. Luckily, relatively little of what most of us do depends on analyzing ever-changing information very fast. The few minutes or seconds of decision-making time we lose is usually more than offset by our crystallized intelligence - the knowledge and experience we also accumulate over the years.
Let\'s illustrate the fluid/crystallized difference by placing odds on a twenty-five-year-old lawyer versus his sixty-year-old opposing attorney to win a court case. The young lawyer, with his fluid intelligence at its peak, could reason and write faster. But our betting odds should be on the seasoned veteran. He is at a clear advantage because of his greater crystallized intelligence, his years of experience in what to research and how best to argue the case.
A study of 150 members of the 1973-74 Vermont legislature makes just this point. Although the younger legislators proposed about twice as many bills, an older legislator\'s chance of getting a given proposal passed was more than twice as great. The slower production rate of the older legislators was easily counterbalanced by the gift that being older conferred: knowing how to prepare legislation better and understanding which types of bills would pass.
There is a physical basis for our gradual loss of fluid intelligence. Our brain cells (neurons) do not send signals and communicate with one another as quickly as they once did. So it takes us more time to process information, from a few milliseconds to a few seconds longer depending on our age, our individual capacities, and the complexity of what we are asked to do. But though this decline is biological, there is an encouraging physical basis for the fact that crystallized intelligence can increase almost to the end of life.
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GENERAL HEALTH
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