From: E
Sent: Friday, March 01, 2019 1:34 PM
Subject: how do you define IQ and tests thereof

Dr. Block:

When I was a troubled teen, I was sent to several therapists to address a diagnosis of  not up to his abilities . I was given an IQ test. Then a month later, with a different therapist, they (unknowingly) gave me the same test a second time. Guess what, I got smarter!

I’m not sure of what these tests measure since they depend on experience quite a bit. Would you agree?

Regards, E

Dear E:

I think IQ tests are pretty accurate; but not perfect.

When I was in grade school, my IQ measurement was 141 (I remember this one exactly). Later on in life, in my 30s, I forget exactly when, I wanted to join Mensa, so I took their IQ test. I failed to join. My IQ tested out at something like 125, and you needed 130, I think, to be accepted. So, I retook the exam, this time, seeing it as a speed test, not an intelligence test. On this retest, I didn’t think, I just sped through the questions. I succeeded this time, with an IQ of about 190. What I got out of this, my surmise, is that the IQ test is pretty accurate for people whose intelligence level is below that of those who wrote the exam, but not for those who are smarter than them. This is just my speculation, based on my own experience, and might be wildly inaccurate.

One further thought. In the bad old days of IQ tests, they would ask questions about a “regatta.” But some people were simply unacquainted with that sort of thing: foreigners, inner city folk, poor people. They don’t do that sort of thing any more. Nowadays, they ask things like, this big circle is to that small circle, as this big square is to what? And then they offer you choices like triangle, parallelogram, circle, small square (the latter is correct). Or they pull this one on you: repeating from memory numbers forward, and numbers backward.  The former does not much distinguish between smart and not so smart people, but the latter does. And no one can complain that repeating numbers backward is culturally or linguistically problematic, since the not so smart people just did almost as well as the smart folk in repeating numbers forward.

Here are some readings on this subject; I hope this disorganized material is of some help to you in your deliberations on this subject:

Murray, Charles. 2007. “Jewish Genius.” Commentary, April

Jewish Genius

In Europe,,2-2105519,00.html,,2-2105519,00.html

Mercer, Ilana. 2005. “The Silly Sex.” Janury 6.

One possible explanation for this discrepancy: the alleged greater variability in men’s intelligence. The “Bell Curve” of their IQ distribution seems to be less bunched around the median IQ than that of women. They are, consequently, more likely to enjoy very high but suffer very low IQs.

The subjects in which so few women have demonstrated excellence require particularly high IQs. And women, so the theory goes, simply have fewer high IQs.

However, Professor Richard Lynn, co-author of IQ And The Wealth Of Nations, argues that men enjoy an advantage in average IQ—their median may be as much as five points above that of women. This means that there are even more high IQ men than women. At an IQ of 145 there are about ten men to one woman. Other author: Tatu Vanhanen

Lynn, Richard and Tatu Vanhanen. 2002.  IQ And The Wealth Of Nations, New York, N.Y.: Praeger Publishers

Lynn, Richard and Tatu Vanhanen. 2006.  IQ and Global Inequality, Washington Summit Publishers

A very good critique of Lynn, Vanhanen:

Unz, Ron. 2012. “Race, IQ, and Wealth: What the facts tell us about a taboo subject”



Seligman, Daniel. 1992. A Question of Intelligence, The IQ Debate in America. New York: Citadel, Carol Press

Seligman, Daniel, “Of Japanese and Jews,” in A Question of Intelligence:

the IQ Debate in America, New York: Citadel, Carol Press, 1994, pp.


Jensen, Arthur R. 1981. Straight Talk about Mental Tests. New York: Free Press; p. 249 There is also an indication that males are slightly more variable in IQ than females, who cluster closer to the general average.

Hence more males are found at the two extremes of the IQ distribution.

There are more males than females above IQ 140 (in the ration of about 1.2 to 1) and below IQ (about 1.6. to 1).”

Levin, Michael. 1987.  Feminism and Freedom. Transaction: New Brunswick, N.J. p. 86.; “The effect observed by Benbow and Stanley is statistically large, in come phases of the study amounting to half a standard deviation.

Boys’ reaching the highest levels of mathematical aptitude thirteen times as frequently as girls would be a miracle on the null hypothesis. More crucially, as I stressed earlier, a big difference is what makes a big difference. Whatever the male mathematical advantage may look like in terms of raw score data, it is large if it explains why men make all the mathematical discoveries, why mathematics is perceived as a masculine skill….”

Benbow, Camilla and Julian Stanley. 1982. “Consequences in High School and College of Sex Differences in Mathematical Reasoning: A Longitudinal Perspective.” American Education Research 19. Winter

Benbow, Camilla and Julian Stanley. 1984. “Gender and the Science Major: A Study of Mathematically Precocious Youth. Advances in Motivation and Achievement. 2.

Benbow, Camilla and Julian Stanley. 1980. Sex Differences in Mathematical

Ability: Fact or Artifact?” Science. 210. December

Benbow, Camilla and Julian Stanley. 1983. Sex Differences in Mathematical Reasoning Ability: More Facts.” Science. 222 December.

Herrnstein and Murray (1994, p. 275). When it comes to gender, the consistent story has been that men and women have nearly identical mean IQs but that men have a broader distribution. In the NLSY, for example, women had a mean on the Armed Forces Qualification Test (AFQT) that was

.06 standard deviation lower than the male mean and a standard deviation that was .11 narrower. For the Wechsler Intelligence Scale for Children, the average boy tests 1.8 IQ points higher than the average girl, and boys have a standard deviation that is .8 point larger than girls. The larger variation among men means that there are more men than women at either extreme of the IQ distribution.

In my view, the cut off point of 140 is woefully low. At a more reasonable cut off point for genius, say, 160, I’ll betcha males outnumber females by a gargantuan proportion. That is the only way to explain gender disparity in chess, math, physics, etc.

Murray on iq:


f-m Iq:

Burgaleta,, 2012; Cooijmans, 2003; Eysenck,1981; Hedges and Nowell, 1995;  Lehrke, R. 1997; Lubinski and Benbow, 2006; Lynn, et. al, 2005; Lynn and Irwing, 2004; Lynn, 2010; Machin and Pekkarinen, 2008; Mills, 2011; Murray, 2011

Burgaleta, Miguel, Kevin Head, Juan Álvarez-Linera, Kenia Martínez, Sergio Escorial, Richard Haier, Roberto Colom. 2012. “Sex differences in brain volume are related to specific skills, not to general intelligence.”

Intelligence; Vol. 40, Issue 1, January–February, pp. 60–68;

Cooijmans, Paul. 2003. “Sex differences in intelligence.”

When it comes to the question whether or not there is difference in mean IQ between males and females, Jensen basically says no, after having considered a large amount of evidence. Eysenck is a little bit more skeptical and points out that the usual assumption of equal IQ of the sexes may be flawed. Based on data also mentioned by Jensen (R. Lynn, 1994, Sex differences in intelligence and brain size: a paradox resolved), Eysenck suggests 4 IQ points as a conservative estimate of the difference (favoring males). Lynn, on his home page, simple states in adults the difference is about 4 points.

Both Jensen and Eysenck indicate that the question is hard to answer, as IQ tests like Stanford-Binet and WAIS have traditionally been constructed to show no sex difference in total score, by leaving out or counterbalancing items that show sex differences. Such tests therefore are not capable of measuring a possible difference between the sexes.

I myself cannot observe a mean difference directly as I only deal with high-range tests. I will return to this point further on with regard to the variance difference.

The male variance in IQ is greater than that for females; Jensen says this difference is greatest in math and spatial ability. In math the male variance is 1.1 to 1.3 times greater (he does not give the difference for total IQ or g).

In the high range, my own observation to date is that at or above the 98th percentile there are about twice more males than females, while at or above the 99.9th percentile there are about 15 times more males. Trying to make this fit in terms of standard deviation (variance is the square of the standard deviation by the way), I find that when the male and female mean are both IQ 100, the male standard deviation (SD) must be about 33% greater than the female SD. However, when a mean difference of 5 points in favor of males would exist, the male SD would only need to be about 11% greater. I don’t know which is true (or if the truth lies in between) and will not be able to verify it myself as I only deal with high-range tests.

I must say though that an SD difference of 33% seems unlikely.

Eysenck, H.J. 1981. Race, Intelligence and Education. Maurice Temple Smith Ltd

Hedges, Larry V. and Amy Nowell. 1995. “Sex differences in mental test scores, variability and numbers of high-scoring individuals.” Science.

Vol. 269, No. 5220, July, pp. 41-45;

Lehrke, R. 1997. Sex linkage of intelligence: The X-Factor. NY: Praeger.

Lubinski, D., & Benbow, C. M. 2006. Study of mathematically precocious youth after 35 years. Perspectives on Psychological Science, 1, 316 – 345.

Lynn, Richard, Adrian Raine, Peter H. Venables, Sarnoff A. Mednick, and Paul Irwing. 2005. “Sex differences on the WISC-R in Mauritius.”

Intelligence, Volume 33, Issue 5, September-October, Pages 527-533;

Lynn, Richard and Paul Irwing. 2004. “Sex differences on the progressive

matrices: A meta-analysis,” Intelligence, Vol. 32, pp. 481–498;

Lynn, Richard. 2010. “Sorry, men ARE more brainy than women (and more stupid too!) It’s a simple scientific fact, says one of Britain’s top dons.” Mail Online, May 8;



Machin, Stephen and Tuomas Pekkarinen. 2008 . “Global Sex Differences in Test Score Variability.” Science. Vol. 322, no. 5906, pp. 1331-1332, November.

Mills, Michael. 2011. “How Can There Still Be a Sex Difference, Even When There Is No Sex Difference? Why men may be more variable on some traits.”

Psychology Today. Jamuary 26;


“This finding of greater male variability in IQ scores has been replicated with many different populations and in more modern times. (See, for example, Hedges and Nowell (1995); and in particular see the appendix of Lubinski and Benbow (2006): Study of mathematically precocious youth after 35 years.)

You may recall that Larry Summers was forced to resign as President of Harvard University when many people simply misinterpreted his remark that males are more variable than are females on many traits:

It does appear that on many, many different human attributes-height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability-there is relatively clear evidence that whatever the difference in means-which can be debated-there is a difference in the standard deviation, and variability of a male and a female population.

Most of his critics misunderstood his remarks and presumed that he was suggesting that males are on average more intelligent than females. Or, if they understood him correctly, some may have found it interesting that there were more intellectually deficient males than females, but the sex ratio at the other tail of the distribution was less palatable. That is, they may have committed the morallistic fallacy — the assumption that if something is morally objectable, either on its face or in its possible misinterpretation or misuse, it cannot be factually correct.

However, if it is simply a fact that males are generally more variable than are females on many traits, why is this true?”

Murray, Charles. 2011. “A big step forward in understanding male-female cognitive differences.” The American Enterprise Blog; the online magazine of the American Enterprise Institute; December 6;


Walter E. Block


12:39 pm on June 25, 2019