Males have greater G: sex differences in general mental ability 	
	
Psychology Posted by Cloud Watcher on Friday September 08, @08:34PM
from the dept.
A study of 100,000 17- to 18-year-olds on the Scholastic Assessment Test published in the September 2006 issue of the journal "Intelligence", has confirmed a surprising new finding: That men have a 4- to 5-point IQ advantage over women by adulthood. Because girls mature faster than boys, the sex difference is masked during the school years, which explains why the sex difference was missed for 100 years.

A study published in the September 2006 issue of the journal "Intelligence" analyzed 145 items from the Scholastic Assessment Test (SAT) in 100,000 17- to 18-year-olds and found a male IQ advantage of 3.63 points.

It also found that the g factor--the general factor of mental ability underlay both the SAT Verbal (SAT-V) and the SAT Mathematics (SAT-M) scales with the congruence between these components greater than 0.90, and that it was the g factor that predicted student grades better than the traditionally used SAT-V and SAT-M scales.

The male and the female g factors were congruent in excess of .99, and they favored males to an equivalent of 3.63 IQ points.

The male-female differences were present at every socioeconomic level, and across several ethnic groups.

The average male advantage was found "throughout the entire distribution of scores, in every level of family income, for every level of fathers' and of mothers' education, and for each and every one of seven ethnic groups," said J. Philippe Rushton, professor of psychology at the University of Western Ontario, one of the authors of the study.

The paper's results dovetail with those from several other recently published studies showing that men--surprisingly--have a 4- to 5- IQ point advantage over women by late adolescence and early adulthood. Before that age the two sexes are equal in general intelligence.

As such, the findings overturn a 100 year consensus that men and women average the same in general mental ability.

Because girls mature faster than boys, the sex difference is masked during the school years. Since almost all the data showing an absence of sex differences were gathered on school children, this might explain why the sex difference was missed for so long.

For decades, however, psychologists have accepted that men and women differ in their test "profiles," with males averaging higher on tests of "spatial ability" and females higher on tests of "verbal ability." These differences were assumed to average out.

The authors of the study, psychologists Douglas N. Jackson and J. Philippe Rushton at the University of Western Ontario, conducted the study because two recent sets of observations had raised anew the question of sex differences in general intelligence.

The first was that the general factor of mental ability--g--was found to permeate all tests to a greater or lesser extent. Thus, a "spatial" test may be relatively high on g (mental rotation) or low (perceptual speed), a "verbal" test may be relatively high (reasoning) or low (fluency), as may a "memory" test be high (repeating a series in reverse order) or low (repeating a series in presented order).

More than any other factor, the test's g loading best determines a test's power to predict academic achievement, creativity, career potential, and job performance. Hence, the question of sex differences became formulated more precisely as: "Are there sex differences on the g factor?"

Another set of observations concerned the sex difference found in brain size and the relation between brain size and cognitive ability. Studies published in 1992 at the University of Western Ontario by zoologist C. Davison Ankney, and also by psychologist Rushton, showed men average a 100-gram advantage over women in brain weight (and volume).
A 1997 study in Denmark documented that men have 15% more neurons than women (22.8 versus 19.3 billion).

Over two-dozen Magnetic Resonance Imaging studies have confirmed a brain-size/IQ correlation of about 0.40. So, if males average a larger brain, shouldn't they also average a higher IQ score?

British psychologist Richard Lynn at the University of Ulster in Northern Ireland, and Paul Irwing at the University of Manchester found that adult men consistently average 4 to 5 IQ points higher than adult women in a series of recent large-scale studies using a number of intelligence tests in various countries. (Irwing & Lynn's most recent paper appeared in Nature on July 6, 2006.)

Other researchers too have found a male advantage in general mental ability, including Prof. Helmuth Nyborg at the University of Aarhus in Denmark, who earlier this year was disciplined by his university for talking to the media about his "politically incorrect" conclusions.

Prof. Rushton agreed that "these are unpopular conclusions." He said, "only more data can determine the true nature of sex differences in cognitive ability. However, people should not be made to feel afraid to study controversial issues."

Prof. Rushton accepted that sex differences in general mental ability could help explain the "glass ceiling" phenomenon.

But he also noted the paradox that although men may have higher IQ scores, women do increasingly well in school exams.

It will be very hard to argue that selection bias caused the sex difference in this data set, the authors wrote. "That would require the assumption that there are hypothetical respondents who, if tested, would provide a compensating female-male advantage in g that would counterbalance the findings. They would have to be found at every level of SAT performance, in every level of family income, for every level of fathers' and of mothers' education, and for every ethnic group examined."

Charles Darwin Research Institute http://www.charlesdarwinresearch.org/

Contact: Prof. J. P. Rushton rushton@uwo.ca

* * * * * * * *

Corresponding author: J. Philippe Rushton, Department of Psychology, University of Western Ontario, London, Ontario, N6A 5C2, Canada Email: Rushton@uwo.ca Tel: 519-661-3685

On the Web: Article pdf: http://www.ssc.uwo.ca/psychology/faculty/rushton_pubs.htm

Full Citation: Jackson, D. N., & Rushton, J. P. (2006). Males have greater g: Sex differences in general mental ability from 100,000 17- to 18-year-olds on the Scholastic Assessment Test. Intelligence, 34, 479-486.

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The Fine Print: The following comments are owned by whoever posted them.
( Reply )

Criticisms of this author
by JW on Sunday September 10, @07:04PM
A friend of mine gave me the following information:

Some highlights of criticism directed towards Rushton and his
"scientific" studies:

"Rushton's sources, such as semi-pornographic books and the Penthouse
magazine, have been dismissed by other researchers, or have been
criticized as extremely biased and inadequate reviews of the
literature, or simply false [9]"


Psychologist David P. Barash wrote in a scholarly review:
I don't know which is worse, Rushton's scientific failings or his
blatant racism.

Dr. Mark Feldman, Stanford University Population Biologist
...concludes that Rushton's work "doesn't really classify as science
... it has no content, it is laughable".[31]

"Rushton is accused by critics of advocating a new eugenics movement
[27], and is openly praised by proponents of eugenics.[28]

"After mass mailing a booklet to psychology, sociology and
anthropology professors across North America based on his racial
papers, Hermann Helmuth, a professor of anthropology at Trent
University, said, "It is in a way personal and political propaganda.
There is no basis to his scientific research."[29]

For more, check out

http://en.wikipedia.org/wiki/J._Philippe_Rushton#Critiques

Or, index Rushton in any psychology or sociology textbook. There will
be pages of criticism directed towards his methodology and his line of
reasoning.



[ Reply to this ]

    *
      Re: Criticisms of this author
      by Psych Student on Saturday September 30, @01:09PM
      It is a shame to see so called controversial science responded to this way. The fact of the matter is this addresses some important questions about human evolution (see runaway selection, mutual mate choice, intelligence as a fitness indicator, etc, etc). These theories are developing to give us a better understanding of how we evolved came to be as we are now. Applications for this research may seem ambiguous now, but so has other pure science before its ramifications could be fully understood. Claiming this is not real science is just silly political propaganda. His critics are likely to have their own political/ideological agendas that skew their perspectives... be they intelligent design theorists, feminists, etc. Remember, many of the scientists we revere today were condemned in their time. Maybe one day we will evolve past that... who knows, maybe this reaction is an evolved mechanism in and of itself. Anyways, all I can suggest is keep an open mind. Just because it is not popular does not make it any less scientific.
      [ Reply to this ]
    *
      Re: Criticisms of this author
      by A. Zarkov on Sunday October 15, @04:26AM
      The critical sections in Wikipedia article on Rushton are almost exclusively personal attacks. Some of the links are dead, and one reference is missing. When you visit the references again all you see is name calling. For example, Rushton is criticized for using the word “Oriental.” Other attacks are guilt by association. The one methodological criticism (Barash) is that he misuses r/k theory. But even this section is mostly a personal attack.

      Now Rushton might be wrong in his methods and conclusions, but you have to provide more than personal attacks. Let’s face it, many people particularly academics, are extremely hostile to anything that might suggest racial or sexual differences. They even deny that races exist at all despite the fact that we can tell a person’s race from his DNA if we use enough markers.

      [ Reply to this ]
          o
            Re: Criticisms of this author
            by A on Sunday October 15, @07:34AM
            They even deny that races exist at all despite the fact that we can tell a person's race from his DNA if we use enough markers.

            Forensic scientists have also been able to identify the race of bodily remains from skull features for quite some time.
            [ Reply to this ]


 
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