Jewish Genius by Charles Murray

"Jews are only about average on the subtests measuring visuo-spatial skills, but extremely high on subtests that measure verbal and reasoning skills."

In explaining Jewish IQ scores Murray writes:

"By way of an analogy, consider written Chinese with its thousands of unique characters. On cognitive tests, today’s Chinese do especially well on visuo-spatial skills. It is possible, I suppose, that their high visuo-spatial skills have been fostered by having to learn written Chinese; but I find it much more plausible that only people who already possessed high visuo-spatial skills would ever devise such a ferociously difficult written language. Similarly, I suppose it is possible that the Jews’ high verbal skills were fostered, through secondary and tertiary effects, by the requirement that they be able to read and understand complicated texts after the 1st century C.E.; but I find it much more plausible that only people who already possessed high verbal skills would dream of installing such a demanding requirement."