A comprehensive study of intelligence differences between ages 6-59
Males and females have shown consistent differences in some cognitive abilities across the lifespan.
A person’s ‘general intelligence’ measured by IQ tests is a ‘higher order’ measure extracted from numerous sub abilities. A study by Keith and colleagues at the university of Texas at Austin has looked at these sub-abilities and general intelligence using state of the art ‘latent variable’ statistical analysis that minimizes the error that can creep into statistical studies giving misleading results. For their age range of interest they drew from a U.S. sample of 8818 children and adults (from 2 to 90 years old) who had been tested on the Woodcock–Johnson III IQ test.
Where men and women are the same
They found no statistically significant sex differences for auditory processing, short-term memory, long-term retrieval, or fluid reasoning.
Where men and women are different
Where they found significant sex differences is shown in the figure below. Differences are in IQ points.
g = general intelligence, RQ = quantitative reasoning, Gv = visual-spatial ability, Gs = processing speed, Gc = comprehension-knowledge (crystallized intelligence).
Interpreting the data
Females show a consistent advantage on information processing speed (Gs) throughout the lifespan – of around 6 IQ points. Girls and women can scan, detect, recognize, compare and discriminate information better. Males have a small (2 point) but consistent advantage on the crystallized intelligence (Gc) comprehension–knowledge ability, including general knowledge. Men will tend to be better at Trivial Pursuit – but only just. Males from 8 years up showed an advantage on quantitative reasoning (RQ) and adult males show a consistent advantage in visual–spatial ability (Gv) . In the 45-59 year old group the difference in these abilities (on average) is 8-10 IQ points. This is a big difference. This is why men may gravitate to maths, architecture, or engineering.
What about general intelligence? Are men smarter?
As for overall general intelligence (g) there were no sex differences for children, small differences for adolescents and fairly consistent significant differences favoring females in adulthood.
This difference in overall IQ level doesn’t show up in some of the popular IQ test measures of intelligence according to the authors because of sources of error and confounds with other abilities (such as spatial abilities) that are controlled for in the latent variable method they use.
So no – men are not smarter. Women are! By 40 years old the difference is 4 IQ points or more.
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Reference
Timothy Z. Keith, Matthew R. Reynolds, Puja G. Patel, Kristen P. Ridley, Sex differences in latent cognitive abilities ages 6 to 59: Evidence from the Woodcock-Johnson III tests of cognitive abilities, Intelligence, Volume 36, Issue 6, November-December 2008, Pages 502-525, ISSN 0160-2896, DOI: 10.1016/j.intell.2007.11.001.
Related posts:
What is the formula for calculating General Intelligence?
How can men be better at three categories of intelligence and have less general intelligence?
Hmmm…
Good question! …the idea is to take out the component of ’shared variance’ for all tests and attribute that to ‘general intelligence’. Where there is variation that is independent from the component common to all tests, you can talk about different ’second level’ factors – such as processing speed, working memory, etc.