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Family size tied to SAT, IQ scores.

When Scholastic Aptitude Test (SAT) scores were nosedriving in the late 1970s--dropping in average from 490 in 1963 to 445 in 1980 -- a presidential commission placed the blame on everything from drugs, pollution and nuclear testing to parental neglect and poor teacher training. But now that SAT scores are climbing steadily, some researchers are reporting that these factors had nothing to do with the decline in the first place. Rather, they say, both the downward and upward trends are dictated primarily by family size: In general, the smaller the family, the higher the children's intellectual development and scholastic achievement.

And because families have become smaller, the current upswing in scores "will continue for another 16 to 18 years," to be followed by another decline, says Robert B. Zajonc of the University of Michigan in Ann Arbor. He and several other scientists report a number of apparently positive effects that small family size has on children's intellectual development. The results were presented this week in Los Angeles at the annual meeting of the American Association for the Advancement of Science.

The current SAT trend fits with the "confluence model," which Zajonc says he first proposed in 1976 to explain the score decline and used at that time to predict that trend's reversal, which began in 1980. According to the confluence model, "the greater the number of children and the shorter the intervals between successive births, the less mature on the average is the intellectual milieu for each child," Zajonc says.

For example, an only child is exposed mainly to his parents' adult environment--the way they interact and deal with their problems -- and to adult language. "In contrast," he notes, "a child in a family of 10, whose oldest sibling is 12, is surrounded by intellectually immature individuals" with less-developed vocabularies.

SAT scores are rising, he says, primarily because of the shrinking U.S. family. In 1962, the average newborn in the United States was the third child, and in 1979, the average U.S. newborn was the second child, says Zajonc, who not only looked at SAT scores but also studied data from the Iowa Basic Skills Test, which is similar to SATs but for children in grades 3 to 12. In scores for this test, he found a decline and subsequent rise consistent with those for the SAT.

Zajonc expects the younger children in the Iowa group, who will be taking SATs between two and 10 years from now, to be part of the continuing upward trend in scores, which he predicts will average between 510 and 515 by the turn of the century. "But because of the rising birth rate after 1980," he says, "a decline [of scores] will follow."

Family size also has a "gigantic" effect on other aspects of a child's education, including grades and whether he or she graduates from high school and goes on to college, says Judith Blake of the University of California at Los Angeles. Analyzing data from two national surveys of 56,000 white fathers, Blake found that next to the father's educational level, family size is the most important predictor of how far a child will progress in school, even more important than the family's socioeconomic status.

"Those [children] from large versus small families," she says, "lose about a year of graded schooling on the average"--mostly in the early grades. These differences between small (defined as one to three children) and large (six or more) families are evident, she says, even when IQ differences are controlled for in the study.

In a separate study of IQ, James V. Higgins of Michigan State University in East Lansing reports that larger families correlate with lower IQs among children. In his analysis of 300 families, Higgins reports that "parents of large families tended to have lower IQs," and concludes that the children, therefore, inherited similar IQ levels. Conversely, he says, "those [parents] with higher IQs tended to produce children with higher IQs."

All the researchers noted that there are, of course, exceptions, but that the large-family versus small-family differences are borne out for large populations. Still, Zajonc points out, an only child may be at a disadvantage in some ways and in fact does not obtain the highest SAT scores. "He has no younger siblings who would seek help and instruction from him," says Zajonc, "no opportunity to serve as an intellectual resource."

According to Zajonc, the findings on family size, paired with Zajonc's and others' results showing that those at the top of the birth order have the highest scores, suggest that the optimal situation seems to be a two-child family with a spacing of more than two years between children.
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Author:Greenberg, Joel
Publication:Science News
Date:Jun 1, 1985
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