In 1992 the journal Psychological Reports published an interesting paper called “JEWISH INMATES: AN ATYPICAL PRISON GROUP” by DONALD I. TEMPLER and PENNY A. JACKSON

The study design was as follows:

All inmates were in the Southern Desert Correctional Center, a medium security prison in whch most convicted felons in the southern half of Nevada are processed and incarcerated. The identities of the 13 Jewish inmates were obtained from prison records and word of mouth; it appears that these men constituted the total population of Jewish inmates.
The quantitative part of this study focused upon two different sorts of information in the records of inmates. One was Raven’s Standard Progressive Matrices percentile based on norms in Table SPM 25 of the manual (Raven,
Court, & Raven, 1986). Because Jews in general tend to score higher than non-Jews on tests of mental ability, it was hypothesized that Jewish inmates would have higher scores on the matrices thin non-Jewish inmates. It was
also hypothesized that Jewish inmates would have fewer violent crimes.

The unstructured interviews were held with a Jewish custody staff Lieutenant, a Jewish Correctional Case Worker Supervisor, and 10 of the 13 Jewish inmates. In addition, a director of a half-way house for the Jewish exfelons in Los Angeles was interviewed by telephone.

Here are the results:

One of the Jewish inmates did not have a Raven’s score or percentile in his records. For the 12 Jewish men who did, nine (75%) were over the 80th percentile of the Matrices manual, but only 27% of the 1477 general population inmates were over the 80th percentile (x2 = 14.03, p< 0.001). Four (31%) of the 13 Jewish inmates and 578 (52%) of the 1477 general population inmates had one or more violent felony convictions (x2 = 2.35, p<0.20).

The 80th percentile is IQ 113 (white norms) so assuming a normal curve and a standard deviation of about 15 for both the Jewish and Gentile inmates, these results suggest the average Jewish prisoner scored IQ 123 and the average Gentile prisoner scored 104.

However the Raven norms were probably about 50 years too old, and it’s well known that Raven ability increased precipitously over the 20th century because of prenatal nutrition and/or schooling (the Flynn effect). It’s also well known that prisoners average IQs around 90. So let’s say the scores were inflated by about 14 IQ points. This would suggest Jewish prisoners have a mean IQ of 109 (19 points higher than their Gentile counterparts!).

Of course with only 12 Jews in the study, one shouldn’t overinterpret these results.

The study is also odd because the Jewish IQ advantage is seen on a non-verbal test where Jews typically have less of an advantage. On the other hand, the Raven aimed to measure higher level conceptual abstract ability that transcends the traditional verbal vs spatial dichotomy.

The authors noted that the Jewish prisoners did not strongly identify with Judaism and had middle class backgrounds. They also showed high achievement motivation.

The authors write:

The reason(s) the Jewish inmates scored higher on the Raven Matrices are not certain. Nevertheless, it should be pointed out that the test is a nonverbal and purported culture-fair test with content that appears less relevant
to formal education than most standard tests of intelligence. Further, Jewish culture is heavily saturated with verbal learning and performance. A large number of Jews do not enter occupations dependent on spatial relations such
as those of machinists, mechanics, draftsmen, and mechanical engineers. To ascribe automatically the high Raven scores entirely to education of high quality or ephemeral characteristics would be simplistic and is unwarranted
at this time.

On the other hand, one of the reasons the Raven has been so sensitive to the Flynn effect is that scores likely can be propped up by education. This seems counter-intuitive because the test is so culturally reduced, but because there’s no time limit and the task is so abstract, educated people likely approach the test with much more confidence, interest, and persistence. By contrast gypsies, who have a subculture quite opposite from Jews when it comes to education, typically dropping out of school in 8th grade, have adult Raven IQs around 70 and complain that it gives them a headache. It would be most interesting to compare the IQs of Roma raised by Ashkenazim and vice versa.