Whence Your IQ?

cover of an old Pete and Clapp book
David Gamson

Illustrations and examples in elementary-school math books, including these from the early 1900s, show an evolution in the teaching of problem-solving which may help explain a general rise in IQ scores.

"If you and I were to go back to the 1930s and take an IQ test, we'd be considered geniuses," says David Gamson, pausing to click on a PowerPoint slide. A line on a graph corresponding to test scores climbs steadily from 1930 to 1990. In just 60 years, the IQ of the average person in the United States has gone up almost 20 points. "We're not the first to notice this phenomenon," says Gamson, a professor of education at Penn State. "But psychologists haven't been able to explain why it happened."

IQ, or intelligence quotient, is a number that purports to describe a person's innate intellectual ability. "The idea of an individual's IQ rising isn't necessarily puzzling since the brain is continually developing," says David Baker, professor of education and sociology at Penn State. "But what is happening in a population to make everyone's IQ rise at the same time?"

Baker, whose research focuses on the societal impact of formal education, hadn't thought much about this question before he met Clancy Blair at Penn State's Children, Youth, and Family Consortium conference on adolescence in 2001. Blair, a professor of human development and family studies and an expert on cognitive development, had been puzzling over the IQ issue. "He approached me, and on the spot we started to pursue the idea of education as a possible reason," Baker remembers. Soon the two had recruited Gamson, an educational historian, and Steve Thorne, an assistant professor in linguistics, into a collaborative effort focused on analyzing changes in school curricula.

According to Baker, "Part of the explanation for rising IQ scores is that a lower proportion of children attended school in the early 20th century than do now. Going to school, period, raises a child's IQ." But more important, he says, are dramatic changes over the last century in what schools teach.

page from old book at Toy Store
David Gamson

"Intelligence is comprised of two components," says Gamson. "Crystallized" intelligence, he explains, is a person's ability to learn and remember facts: vocabulary, names, basic equations, and the like. "Fluid" intelligence is something more general: a person's problemsolving skills; the ability to take information and perform an operation on it. It's the latter component, he says, that has jumped precipitously in IQ scores. The one school subject that relies most heavily on fluid intelligence, Blair adds, is mathematics. "That makes math the logical choice for tracking curriculum changes."

To begin their study, the team analyzed elementary-school math books—kindergarten through sixth grade—from the early 1900s to the present.

Before mid-century, "Educators believed that math should not be taught until after children could read," Gamson says. What math instruction children did receive was mostly counting. Gamson points to a first-grade textbook from 1911 entitled First Journeys in Numberland, a thin volume that looks more like a reader than a math book. There are no numbers "only words and illustrations. On a typical page, a drawing shows a group of children in a classroom, some sitting on the floor, and some on a bench. Count the boys on the bench, the text reads. How many boys? Notes Blair, "The problems exercise only rote counting, a component of crystallized intelligence."

In the 1920s and 1930s, Blair says, textbooks began to include categorization along with counting. "Categorization requires children to make multiple operations when performing a task," he says, "holding in mind the need to categorize and the need to count and then executing both simultaneously." Gamson points to an example in a first/second grade book, published in 1930. On a page depicting an outdoor fair scene, readers are asked to count the number of large balloons as opposed to the number of small ones.

It was not until the early 1960s that visual-spatial problem-solving, what Blair calls "a central aspect of fluid intelligence," became a standard part of elementary math curricula. This type of problemsolving, he explains, requires a skill known as "mental rotation," i.e., the ability to simultaneously hold an image in the brain and perform functions on it.

An 1894 college textbook, for example, includes a problem that requires drawing and cutting out a two-dimensional triangle, then folding the triangle to transform it into a three-dimensional polyhedron.

page from old book with birthday party
David Gamson

By 1955, this type of problem was being included in seventh-grade textbooks, the researchers found. By 1971, it was being taught to third-graders, and by 1991, a first-grade textbook includes a simplified version of the concept.

The evolution in math books, Gamson concludes, would seem to support the team's original hypothesis about a curriculum's impact on IQ scores. "But we're far from being finished," he notes. "We have yet to look at a multitude of other factors that could impact fluid intelligence." One is changes in textbook language.

This May, the team plans to assess the impact of changing curricula on the brain directly, working with neurologists at the Hershey Medical Center to conduct functional MRI scans of children in the act of learning. A functional MRI, Baker explains, creates snapshot images of the brain over time, highlighting specific areas as they are activated in response to changing stimuli. By scanning elementary-school volunteers while they work at different types of math problems, Baker says, "We want to see what parts are exercised in response to what levels of curriculum."

"It's a well-established fact that the frontal lobe is related to fluid intelligence," Blair adds. "What we hope to demonstrate is that the frontal lobe shows increased activation in response to the changes in math that we believe are partly responsible for the increase in intelligence over the last 100 years."

David Baker, Ph.D., is professor of education and sociology, 603 Oswald Tower, University Park, PA 16802; 814-863- 0955; dpb4@psu.edu. Clancy Blair, Ph.D., is assistant professor of human development and family studies, S110 Henderson Bldg., 863-6423; cbb11@psu.edu. David Gamson, Ph.D., is assistant professor of education, 310E Rackley Bldg., 865- 2583; dag17@psu.edu; Steve Thorne, Ph.D., is assistant professor of applied linguistics, 305 Sparks Bldg., 863-7063; sthorne@psu.edu.

Last Updated September 01, 2003