These are the kinds of questions that Ye Li, an assistant business professor at University of California-Riverside and his colleagues attempted to solve in a recent study, "Complementary Cognitive Capabilities: Economic Decision Making, and Aging," just published in the American Psychological Association's journal Psychology and Aging.
In case your subscription hasn't arrived in the mail yet, here's a quick outline of Professor Li's findings.
Smart Eggs, Savvy Chickens
As anyone who's tried to pick up a foreign language after graduating from college can tell you, the human brain tends to ossify with age. Learning new things gets harder and harder, the older you get.
Li and his team call this ability to learn new things "fluid intelligence." They note that it can be particularly important in helping younger people to process new information (such as learning how to "tweet" or "twerk") and facilitate decision-making.
On the other hand, it's a simple truism that the older you get, the more experience you rack up.
Advantage: Youth and Beauty
Which of these kinds of intelligence is more important for investors?
Forming two test groups, the first of 173 young adults ages 18 to 29, and the second of 163 seniors ages 60 to 82, Li's team put each group through a battery of tests to measure their fluid and crystallized intelligences, and to evaluate how well they made economic decisions.
What they found out was, in part, exactly what you'd expect: While the senior group had accumulated more financial knowledge (facts), the younger group had a significant advantage in fluid intelligence (the ability to learn new things).
Bigger Advantage: Age and Wisdom
What was more surprising -- and perhaps more encouraging -- is that over time, what seniors lose in fluid intelligence, they more than make up for with accumulated crystallized intelligence.
For example, when tested for their skill in estimating and weighing the importance of future losses and gains on investments, understanding financial information, and understanding how debt and interest rates work, seniors "performed as well as or better than younger participants on all decision-making measures."
Crunching the numbers, Li and his team concluded that even if fluid intelligence does decline with age, "older adults' higher levels of crystallized intelligence can provide an alternate pathway to good decisions."
In particular, financial literacy is like fine wine: It improves with age. What's more, understanding the effects of debt appears to increase significantly with age -- knowledge that one imagines may have been painful to acquire.
Fortunately, the two types of intelligence appear to be complementary -- such that a store of crystallized intelligence can make up for dwindling reserves of fluid intelligence.
Based on their results, Li and his team concluded that "older people were somewhat better decision-makers than younger people ... Having greater experience and acquired knowledge from a lifetime of decision making may have provided older people with another way to make good decisions."
Moral of the story: If a young Harvard Business grad tells you to buy a stock, but Warren Buffett says to sell it, listen to Mr. Buffett.
Motley Fool contributor Rich Smith worries he's too old to learn new tricks easily, but not yet old enough to have attained wisdom.