Murder rates affect IQ tests scores: study

Mon Jun 14, 2010 5:36pm EDT
 
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By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - A murder in the neighborhood can significantly knock down a child's score on an IQ test, even if the child did not directly witness the killing or know the victim, U.S. researchers reported on Monday.

The findings have implications both for crime control efforts and for the heavy reliance on standardized tests, said New York University sociology professor Patrick Sharkey, who conducted the study.

They can also explain about half the achievement gap between blacks and whites on such tests, he reported in the Proceedings of the National Academy of Sciences.

"It means being more aware of the potential for violence to have a reach that extends beyond just those victimized and those who witness a violent event, to reach across a community and affect all children in a community," Sharkey said in a telephone interview.

Sharkey compared data on crimes broken down to within a few blocks in a neighborhood with school test scores.

He collected details of more than 6,000 murders in the Chicago area and the results of two surveys of children and families in Chicago neighborhoods. The surveys included scores from tests that are used to determine a child's IQ.

If a murder occurred in a child's neighborhood -- an area of roughly six to 10 square blocks as denoted by the U.S. Census -- the children's test scores fell by an average of half a standard deviation, Sharkey reported.

On an IQ test using 100 as the average or norm, one standard deviation is 15 points. So if a child took the test within a week of a local murder, his or her score was 7-8 points lower on average than the score of a similar child in a similar neighborhood where there was no murder.   Continued...