If you think your IQ is something you're born with, you need to hit the books. A Psychology Today article by Cornell University psychology professor Stephen J. Ceci reveals some fascinating facts about IQ. Among them:
1. Staying in school makes you smarter. It's not just that you know more facts. Each month you stay in school helps bolster your IQ.
Evidence of this goes back about 100 years, to when the London Board of Education studied a group of low-IQ kids. They compared kids within families, and the more school kids missed as they aged, the lower their IQs were. This suggests that IQ isn't a fixed gift--it blooms if we nourish it and withers if we don't.
Some interesting studies:
- The draft at the end of the Vietnam War was lottery-based. Men born on July 9, 1951, had incentive to stay in school, because they were the first to be picked. By contrast, men born July 7 were last picked, and had less incentive to stay in school. The men born July 9 tested at higher IQs and earned about 7 percent more money at work.
- Dropouts lose IQ points. Swedish researchers found a 1.8-point IQ loss for each year of high school missed after dropping out.
- Summer vacation means brain drain. Two independent studies show an IQ decline over the summer, increasing with every month out of school. Kids hit hardest are the ones with the least academic orientation.
2. Your birthdate could affect your IQ. If you're born in the last three months of the year, your IQ could be a victim of school policies. Schools usually have cutoff dates; if you're born after one, you have to wait a year to start kindergarten. Likewise, schools also require attendance until kids are 16 or 17. But 16-year-old dropouts born after the cutoff date get a year less of schooling than 16-year-olds born before it. And researchers have shown that each year of schooling is good for about 3.5 IQ points. So even though kids born in the last three months of the year have the same intellectual potential, school rules can come back to bite them harder than their peers if they drop out.
3. That book-smarts-vs.-street-smarts thing is true. A Yale psychologist demonstrated in 1995 that practical intelligence and analytical intelligence aren't related, But practical intelligence--also known as common sense--is an important predictor of whether you'll be a success. The same goes for intellectual ability. It's linked to earning higher wages. Even with the same amount of schooling, higher-IQ people earned more. So theoretically, high-IQ people with street smarts are the luckiest of them all.
Intelligence breaks down along more lines than book- vs. street-smart. Researchers have measured spatial, verbal, and analytical intelligences, and Howard Gardner of Harvard argues for even more categories, including interpersonal, intrapersonal, linguistic, motor, and musical intelligences.
4. You're probably "smarter" than your grandpa. At least, as measured by IQ tests. If you could turn back time 50 years and take an IQ test, more than 90 percent of today's scorers would rate "genius." Meanwhile, our grandparents' scores compared to today's would tend to put them in one of the lowest buckets. Does this mean we're actually smarter? Not so much. Rather, we have better nutrition, more schooling, better-educated parents, and lifestyles that have been enriched by computers and toys that boost that particular kind of intelligence. In other words, we test better.
5. What you put in your mouth can affect your brain. A study of 1 million students in New York City revealed that school pupils did 14 percent better on IQ tests after preservatives, dyes, and artificial flavors were removed from their lunches. The weakest students benefited the most from healthier food.
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