IQ to the Test

Eleven facts about intelligence that will astound the experts. Who has it and how do we measure it?

By Stephen Ceci, published on July 01, 2001 - last reviewed on May 09, 2006

FACT 10: IQ is on the rise

IQ has risen approximately 20 points with every generation, a steady increase called the "Flynn Effect," after New Zealand political scientist James Flynn. If people taking an IQ test today were scored with the norms of their grandparents' performances 50 years ago, more than 90% of them would be classified as "geniuses," while if our grandparents were scored today, most of them would be classed as "borderline mentally retarded." No one believes that real intelligence has risen as swiftly as IQ—if our grandparents were born today, they'd do just as well on IQ tests as they did a half century ago.

The rise in IQ has been attributed to many factors, such as better nutrition, more schooling, better-educated parents and more complex spatial environments thanks to smart toys and computers. The rise in IQ suggests that whatever it is that IQ tests test, it is not some inherent quality of the mind.

FACT 11: IQ my be influenced by the school cafeteria menu

Recent research appears to confirm our mothers' wisdom that diet influences brain functioning. Eat your fish; it's brain food.

In one large-scale analysis of approximately 1 million students enrolled in the New York City school system, researchers examined IQ scores before and after preservatives, dyes, colorings and artificial flavors were removed from lunch offerings. They found a 14% improvement after the removal. And the improvement was greatest for the weakest students. Prior to the dietary changes, 120,000 of the students were performing two or more grade levels below average. Afterward, the figure dropped to 50,000.

Intelligence, IQ, heredity and ecology are intertwined in complex and intriguing ways. Technical journals are awash with data, and one should consider the facts before leaping to conclusions about what is and what is not intelligence. We should all challenge the implicit theories of intelligence; otherwise we are in danger of misinterpreting the truth.