Jim Flynn’s latest book has fascinating info on age and intelligence.  But Sternberg, Wagner, Williams, and Horvath, “Testing Common Sense” (American Psychologist, 1995) suggest that Flynn misses an important part of the story. 

There’s a widespread perception that “common sense” improves with age:

Older adults commonly report growth in practical abilities over the years, even though their academic abilities decline. Williams, Denney, and Schadler (1983) interviewed men and women over the age of 65 about their perception of changes in their ability to think, reason,and solve problems as they aged. Although performance on traditional cognitive ability measures typically peaks at the end of formal schooling, 76% of the older adults in the Williams et al. (1983) study believed that their ability to think, reason, and solve problems had actually increased over the years, with 20% reporting no change and only 4% reporting that their abilities had declined with age. When confronted with the fact of decline in psychometric test performance upon completion of formal schooling, the older sample said that they were talking about solving different kinds of problems than those found on cognitive ability tests–problems they referred to as “everyday” and “financial” problems.

And this perception is probably correct:

The idea that practical and academic abilities follow different courses in adult development finds support in a variety of studies. For example, Denney and Palmer (1981) gave 84 adults between the ages of 20 and 79 years two types of reasoning problems: a traditional cognitive measure, the Twenty Questions Task (Mosher & Hornsby, 1966); and a problem-solving task involving real-life situations such as, “If you were traveling by car and got stranded out on an interstate highway during a blizzard, what would you do?” or, “Now let’s assume that you lived in an apartment that didn’t have any windows on the same side as the front door. Let’s say that at 2:00 a.m. you heard a loud knock on the door and someone yelled, ‘Open up. It’s the police.’ What would you do?” The most interesting result of the Denney and Palmer study for the purposes of this article is a difference in the shape of the developmental function for performance on the two types of problems. Performance on the traditional problem-solving task or cognitive measure decreased linearly after age 20. Performance on the practical problem-solving task increased to a peak in the 40 and 50 year-old groups, then declined.

This certainly fits my experience.