Dr. Richard Lynn The Intelligence of American Jews Sat Feb 14 01:24:26 2004 64.140.158.107 The Intelligence of American Jews Dr. Richard Lynn University of Ulster, Coleraine, Northern Ireland http://www.rlynn.co.uk Summary. This paper provides new data on the theory that Jews have a higher average level of verbal intelligence than non-Jewish whites. The theory is considered by examining the vocabulary scores of Jews, non-Jewish whites, blacks and others obtained in the American General Social Surveys carried out by the National Opinion Research Centre in the years 1990-1996. Vocabulary size is a good measure of verbal intelligence. Jews obtained a significantly higher mean vocabulary score than non-Jewish whites, equivalent to an IQ advantage of 7.5 IQ points. The results confirm previous reports that the verbal IQ of American Jews is higher than that of non-Jewish whites. Key words: Jews, intelligence Introduction It has often been asserted that Jews have a higher average level of intelligence than non-Jewish whites of European origin. Herrnstein and Murray (1994, p.275) have written that "Whenever the subject of group differences comes up one of the questions sure to be asked is 'Are Jews really smarter than everyone else?' ” and their answer to this question is an affirmative. Eysenck (1995,p.159) asserted that "As far as Jews are concerned, there is no question that they score very highly on IQ tests". Levin (1997,p.132) has written that “in every society in which they have participated, Jews have eventually been recognised (and disliked for) their exceptional talent”. Seligman (1992, p.133) writes of "the extraordinarily high Jewish g levels”. Despite these assertions, the purported high IQ of the Jews has never been systematically reviewed and is not even mentioned in recent textbooks on intelligence, such as those of Brody (1992) and Mackintosh (1998). There have nevertheless been a number of studies of the intelligence of Jews in the United States. Among those who have discussed this question, there is a general consensus on two points. First, that Jews have a higher average IQ than gentile whites (this term is used for non-Jewish whites). Second, that Jews are stronger on verbal ability than on visualization and visual-spatial ability. Beyond this, there is a considerable range of conclusions. A review by MacDonald (1994,p.190) concludes that “taken together, the data suggest a mean IQ in the 117 range for Ashkenazi Jewish children, with a verbal IQ in the range of 125 and a performance IQ in the average range”. Storfer (1990,p.314) writes that “Jewish people, considered as a group, tend to excel in some cognitive domains – for example, verbal and numerical ability – but not in others, as witness their unexceptional performance on certain types of spatial or perceptual problems. Storfer concludes that American Jews have an average IQ of about 112 on the Stanford-Binet, largely a test of verbal ability. Herrnstein and Murray (1994, p.275) reach a similar conclusion “A fair estimate seems to be that Jews in America and Britain have an overall IQ mean somewhere between a half and a full standard deviation above the mean, with the source of the difference concentrated in the verbal component” (1994, p.275). In the sample they analysed, Jews had an average IQ of 112.6 in relation to American whites on four verbal subtests (word knowledge, paragraph comprehension, arithmetic and mathematics) of the AFQT (Armed Forces Qualification Test). Their estimate of a Jewish advantage of between a half and a full standard deviation is equivalent to an IQ range of 7.5 to 15 IQ points. The estimates proposed by Storfer and Herrnstein and Murray are similar but much lower than that suggested by MacDonald (1994). Despite the widespread consensus on the high Jewish verbal ability, not all studies have shown that Jews have a higher verbal IQ than gentiles. Furthermore, virtually all the existing studies are unsatisfactory because the samples have been unrepresentative, very small or for other reasons. An early study carried out in the mid-1920s of 702 Jewish and 1030 non-Jewish white 9-13 year olds tested with the Pintner-Cunningham test (a largely verbal test) by Hirsch (1926) found the Jewish children obtained a mean IQ only 1.5 IQ points higher than the gentiles. However, at this time a number of Jewish families spoke Yiddish as their first language and this would have handicapped the children to an unknown extent. A later study by Shuey (1942) of students entering Washington Square College in New York in 1935-7 tested with the American Council Psychological Examination, a test of verbal abilities (with subtests of completion, arithmetic, artificial language, analogies and opposites) found that 764 Jewish freshmen scored 1.2 IQ points below 236 non-Jewish whites. All the students were native born, possibly suggesting that the performance of the Jewish students was unlikely to have been depressed by unfamiliarity with the English language although some of these may still have been speaking Yiddish as their first language. Furthermore, Jewish and gentile students at this college cannot be regarded as respresentative of their respective communities. A more recent study by Hennessy and Merrifield (1978) with an impressive sample size of 2,985 Jewish, gentile, black and Hispanic college bound high school seniors found a difference of less than 1 IQ point between Jews and gentiles on tests of verbal ability and reasoning but the sample may not have been representative of the populations. Another problem with a number of the studies that have found that Jews have higher verbal IQs than gentiles is that several of them are based on very small sample sizes. For instance, Seligman (1990, p.130) writes that “Jewish verbal superiority appears unmatched in any other ethnic group. An often-quoted 1970 study performed by the Ann Arbor Institute for Social Research shows Jewish tenth-grade boys with an average verbal IQ equivalent of 112.8 (on the Stanford-Binet metric) about three quarters of a standard deviation above the average for non-Jewish white boys”. This is the Bachman (1970) study in which the number of Jewish boys was 65. In the Herrnstein and Murray (1994) data set in which Jews obtained a mean verbal IQ of 112.6, the sample size was 98 and was not drawn to be nationally representative. There is only one study of the intelligence of American Jews in the last half century which appears to be representative and had a reasonable sample size. This is Backman’s (1972) analysis of the data in Project Talent, a nationwide American survey of the abilities of 18 year olds carried out in 1960. The study had sample sizes of 1,236 Jews and 1,051 white gentiles (in addition to 488 blacks and 150 Orientals). IQs for six factors were calculated. The mean IQs of the Jews in relation to gentile white means of 100 and standard deviations of 15 were as follows: verbal knowledge (described as “a general factor, but primarily a measure of general information” and identifiable with Carroll’s (1993) gc or verbal comprehension factor - 107.8; English language – 99.5; mathematics – 109.7; visual reasoning (“a measure of reasoning with visual forms”) – 91.3; perceptual speed and accuracy – 102.2; memory (short term recall of verbal symbols) – 95.1. These results are consistent with the general consensus that Jews perform well on tests of verbal ability (although not of English language) and mathematics and less well on visual and spatial tests but the verbal IQ of 107.8 is towards the low end of the estimates of Jewish verbal ability suggested by Herrnstein and Murray of an IQ between 107.5 and 115. However, the differences in the IQs for the various abilities are so great as to raise doubts about the results. The existing state of the research literature on the IQ of American Jews is therefore that some studies have shown that their verbal IQ is about the same as that of gentile whites while other studies have shown that it is considerably higher at 107.8 (Backman, 1972), 112.6 (Herrnstein and Murray, 1994) and 112.8 (Bachman, 1970). However, the last of two of these studies have sample sizes of fewer than 100. There is room for more data on the IQ of American Jews, and it is to the presentation of this that we now turn. Method The American National Opinion Research Center (NORC) in Chicago carries out annual surveys on approximately 1,500 individuals in continental United States (ie. excluding Hawaii and Alaska). The samples are representative of the adult population of those aged 18 years and over except that they exclude those who cannot speak English and those resident in institutions such as prisons and hospitals. Full details of the sampling procedures are given by Davis and Smith (1996). The NORC surveys collect a vast amount of information about the respondents' opinions on a variety of topics and also on their demographic characteristics such as their income, education, age, ethnic group, religion, etc.etc. The first items of information of particular interest to us are the respondents' religion and ethnic group. An analysis of these enables us to categorise the respondents as Jewish, non-Jewish white, black and other. The second item of interest is the respondents' score on a 10 word vocabulary test. Vocabulary is a good measure of both general intelligence and verbal intelligence. For instance, in the standardisation sample of the Wechsler Adult Intelligence Scale (WAIS) the vocabulary subtest correlates .75 with the Full Scale IQ, more highly than any other subtest (Wechsler,1958) and the Full Scale IQ is widely regarded as a good measure of general intelligence or Spearman’s g (Jensen, 1998). We are therefore able to examine the vocabulary scores as a measure of the verbal and general intelligence of the four religious/ethnic groups. As noted, the annual NORC surveys are carried out on approximately 1,500 individuals. A single year does not therefore provide many Jews. To rectify this problem we can take the results of a number of years and combine them. This gives rise to a further problem that the vocabulary test has not been administered in every annual survey. From 1990 onwards, the vocabulary test was given in 1990, 1991, 1992, 1994 and 1996. The data collected in these years are used to analyse the vocabulary scores of the four ethnic/racial groups. Results The results are shown in Table 1. Reading from left to right, the columns show the numbers in the four groups, the mean vocabulary scores, standard deviations and conventional IQs based on a gentile white mean of 100 and standard deviation of 15. Thus, expressed in this way, the Jewish group obtains a mean IQ of 107.5, significantly higher than the gentile whites (t=5.82); the blacks obtain a mean IQ of 89.7, significantly lower than that of gentile whites (t=17.89); the “others” obtain a mean IQ of 98.6, not significantly different from that of gentile whites. Table 1. Vocabulary scores and verbal IQs of American Jews, non-Jewish whites, blacks and others. Ethnic Group N Mean Sd IQ Jews 150 7.32 2.16 107.5 Gentiles 5300 6.28 2.03 100.0 Blacks 806 4.96 1.94 89.7 Others 219 6.09 2.37 98.6 Discussion The results provide seven points of interest. First, they confirm the previous studies showing that American Jews have a higher average verbal intelligence level than non-Jewish whites. Second, the 7.5 IQ point Jewish advantage is rather less than that generally proposed and found in the studies reviewed in the introduction finding that Jews have verbal IQs in the range of 110-113 but is closely similar to the figure of 107.8 obtained in the Bachman study which is arguably the most satisfactory of the previous studies in terms of the size and representativeness of the sample. Third, the present data has strengths in comparison with a number of previous studies in so far as they are based on a nationally representative and reasonably large sample size of 150 Jews and 5,300 gentile whites. The very close similarity between the present result and the Bachman result suggests that the best reading of the verbal IQ of American Jews is 107.5 (present study) or 107.8 (Bachman). These figures are well below previous estimates of Jewish verbal ability. Four, an average verbal IQ of 107.5 would confer a considerable advantage for American Jews in obtaining success in professional work. There would be approximately four times as many Jews with IQs above 130, compared with gentile whites. This may provide a plausible explain for the 4.8 over-representation of Jews listed in American reference books of the successful such as Who’s Who, American Men and Women of Science, The Directory of Directors, The Directory of Medical Specialists and the like and calculated by Weyl (1989). Five, the small difference of 1.4 IQ points between the non-Jewish whites and the “other” category is not statistically significant or very informative. The category is largely made up of Hispanics and Asians, which are themselves a heterogeneous category. Hispanics have mean IQs below whites (e.g. Herrnstein and Murray,1994), East Asians have about the same IQ as whites (Flynn, 1992) or slightly higher than whites (Lynn,1995), while South Asians have mean IQs lower than those of whites according to the calculations of Flynn (1992). Aggregating these groups produces a combined mean very close to that of non-Jewish whites. Six, despite some three quarters of a century of research and quite a number of papers on the intelligence of American Jews there is still a lot of useful research to be done on this question. Probably the best approach would be to analyse Jewish abilities in terms of the construct of g and of the eight second order cognitive factors in the taxonomy of intelligence proposed by Carroll (1993) and the similar taxonomy advanced by McGrew and Flanagan (1998). These second order factors are fluid intelligence (reasoning), crystallized intelligence (verbal comprehension and knowledge), general memory and learning, visualization, broad retrieval ability, cognitive speed and processing speed. Probably all that can be concluded with a fair degree of confidence at present is that Jews have high crystallized intelligence (verbal ability) of which the vocabulary test used in the present study is a good measure and that on this ability their IQ in relation to gentile whites is approximately 107.5. The Backman (1972) provides IQs for several of the second order factors (given in the introduction to this paper) but these are so variable and in some instances so low as to raise doubts about their credibility. It is difficult to credit that the Jewish sample could have a non-verbal reasoning IQ of 91.3, and at the same time a mathematical IQ (“quantitative reasoning” in the McGrew and Flanagan taxonomy) of 109.7. It is also difficult to credit that the Jewish sample could have a verbal IQ of 107.8 while at the same time having a short term verbal memory IQ of 95.1. These results are in need of checking and replication. At present it is doubtful whether any conclusion can be reached about the intelligence of American Jews except that their verbal intelligence or, if this is preferred, their gc (crystallized intelligence) is about 107.5. Seven, the factors responsible for the high Jewish verbal IQ raise interesting questions. It has been proposed by MacDonald (1994) that these lie in centuries of eugenic customs, especia