I’ve been informed in the comments by William that Wikipedia is claiming Ashkenazi Jews have a mean verbal IQ of 125.6!  Although I’d like to believe this because it would nicely explains the incredible economic and cultural achievements of U.S. Jews, it’s hard to believe a people so genetically related to whites and Arabs could have a verbal IQ dozens of points higher than both.

I decided to turn to chapter 10 of my hero Daniel Seligman’s excellent 1992 book A Question of Intelligence, since Seligman was especially curious about how his people scored on IQ tests.  I learned that most studies of American Jews are not very representative, because samples are often drawn just from New York city or from children in Orthodox schools.

Seligman notes that the closest thing we have to a representative sample is Project Talent, a wide ranging survey, done in the early sixties, of Caucasian high school students.

Seligman writes:

The students were given an exhaustive battery of tests (forty-nine in all!) when they were in the ninth grade, then tested again (though not on all forty-nine) in the twelfth grade.  The Project Talent data included results for 1,236 Jewish students.

Seligman then goes on to quote a summary of the results from scholar Miles D. Storfer.

Jewish math IQ 113

Storfer writes:

The scores of the Jewish boys averaged almost a full standard deviation above those of non-Jewish boys, and the Jewish girls’ scores exceeded those of their non-Jewish counterparts by a nearly equivalent degree (0.75 standard deviations); because boys substantially outperform girls on this test, the average score of the Jewish boys was in the top 1 percent of all test takers.

Averaging boys and girls together, it seems U.S. Jews outperform whites by 0.88 standard deviations (SD), implying the average math IQ of 113 (white norms).  Of course this is approximate because IQs are calculated with reference to sex-combined norms, which don’t necessarily correspond to the average within sex norms.  I’m also baffled as to how the average Jewish boy could possibly be in the top 1% of the sex combined sample (implying an astonishing math IQ of 135) if they are only 1 SD higher than white boys, unless the male SD is far higher than the sex-combined SD and/or the sex gap is absolutely colossal.

U.S. Jewish verbal IQ 109

Storfer writes that on verbal knowledge:

…Jewish boys’ scores averaged 0.7 standard deviations higher than those of the non-Jewish boys, and the Jewish girls outperformed their non-Jewish Caucasian counterparts by slightly more than half a standard deviation.

So averaging both sexes together, we see Jews are +0.6 SD on white norms, suggesting an average verbal IQ of 109.  That’s an incredibley impressive average for an entire U.S. ethnic group, but it’s nowhere near the verbal IQ of 125.6 claimed by Wikipedia.

U.S. Jewish processing speed IQ 100

Storfer writes that on measures of perceptual speed and accuracy, “…non-Jewish students were on par with the Jewish students in this test of visual-motor coordination under speeded conditions…”.  Note that psychometric processing speed should never be confused with chronometrics as the two measures have relatively low correlations.

U.S. Jewish grammar IQ 100

Storfer notes that non-Jews also matched Jews “on a test of grammar and language use.”

U.S. Jewish spatial IQ 93

Storfer notes that on reasoning with spatial forms, “…Jewish students scored significantly less well on this test (half a standard deviation lower than the non-Jewish sample)”  This implies an average spatial IQ of about 93.

U.S. Jewish memory IQ 96

Storfer notes that Jews “also performed poorly on a measure of short-term recall of sequences of nonword letter strings (scoring 0.3 standard deviations below the non-Jewish sample).”  This implies a memory IQ of 96.

U.S. JEWISH OVERALL IQ 102?

Given such a wide range of scores, it’s fascinating to ask what the overall Jewish IQ is.  Averaging across all six subtests, Jewish Americans outperformed U.S. whites by 0.12 SD.  Converting that into a composite IQ requires knowing the intercorrelations of the subtests, however on a comparable battery of tests (the WISC-R), someone who averages +0.12 SD across all the subtests has a composite score that is +0.13 SD, equating to a full-scale IQ of 102.

This is substantially lower than the U.S. Jewish mean of 110 commonly cited by Richard Lynn.  Of course it depends on the test. If one goes by tests like the SAT, which are all about verbal and math talent, Jews should easily score 110, but on a more comprehensive global sample of intellectual abilities,  it seems U.S. Jews are virtually tied with U.S. whites.

So it depends how you want to define intelligence.  I like to define it as the mental ability to adapt: to take whatever situation you’re in, and turn it around to your advantage.  For the last 100 years or so Jews have been incredibly adaptable, emerging as 36% of U.S. billionaires and 50% of media pundits, despite being only 2% of America.  However in the early 20th century, Jews were poor, and their intellectual achievements were scarce before the 19th century.

Why did Jews struggle to adapt for so long, and then suddenly start thriving economically and culturally?  Is this because Jews only recently evolved their high IQs as scholars Cochran and Harpending argued, or did their genes stay the same, while the environment suddenly began to favour their specific cognitive talents (verbal and math)? Spatial IQ might be useful for building a civilization, but once the buildings and technology is built by others, wordsmiths and math types rule the roost.

Ashkenazim IQ in Israel, 8 points lower than in the U.S.

But one reason it’s hard to believe that the mean U.S. Jewish IQ is 102 is that American Jews are perhaps the elite of worldwide Jewry. In the 2006 book Race Differences in Intelligence (pg 94), Richard Lynn claimed that Ashkenazim in the U.S. and Britain averaged 107-115, while Ashkenazim in Israel averaged 103 (eight points lower).  But if U.S. Jews average only 102 on a more complete measure of IQ, does that means Israeli Ashkenazim average only 94?

Although such figures would be consistent with the slightly smaller brain size that’s been found among Jews and Israel’s dependence on U.S. support, it is inconsistent with the incredible scientific achievements of Jews throughout the 20th century.