Bigger brains don't score higher on IQ tests

Analysts point to the superior significance of brain structure -- not size -- in predicting intelligence.

By Brooks Hays

GOTTINGEN, Germany, Oct. 14 (UPI) -- Bigger may be better, but not necessarily when it comes to brain size and intelligence.

For decades, centuries even, scientists have looked at the relationship between brain size and smarts. The results have been inconclusive, at best.


Recently, researchers looked to offer some clarity (and maybe some finality) on the subject with a meta-analysis of some 148 studies comprising data on the brain sizes and IQ scores of more than 8,000 participants.

The analysis showed only a weak relationship between the size of a person's brain and their IQ score. Though many studies found larger brains were linked with higher IQ scores, the predictive value of brain size was deemed to be minimal.

The new meta-analysis -- carried out by researchers from Austria, Germany and Netherlands and published in the journal Neuroscience and Biobehavioral Reviews -- suggests the role of brain size in determining IQ has been exaggerated and oversold in the scientific literature.

"While it is tempting to interpret this association in the context of human cognitive evolution and species differences in brain size and cognitive ability, we show that it is not warranted to interpret brain size as an isomorphic proxy of human intelligence differences," researchers concluded in their paper on the subject.


The researchers used the differences between men and women as evidence of their general conclusion. Men have consistently larger brains than women, but there is no difference between the sexes when it comes to global IQ test performance.

Instead, the analysts point to the superior significance of brain structure.

"Brain structure and integrity appear to be more important as a biological foundation of IQ, whilst brain size works as one of many compensatory mechanisms of cognitive functions," Jakob Pietschnig, a researcher at University of Vienna's Institute of Applied Psychology, said in a press release.

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