Irwing, P., Booth, T., Nyborg, H., & Rushton, P.
In: 11th Annual Conference of the International Society for Intelligence Research. ;
Washington, USA. 2010.
Life history (LH) theory posits that clusters of correlated traits lie on a continuum.
Fast strategies are hypothesized to evolve in harsh and unpredictable environments,
while the reverse holds for slow strategies. Previous research has shown that a slow
strategy correlates with law abidingingness, behavioural restraint, maturational delay
and longevity. Diverse characteristics are predicted to correlate together as a suite
of characteristics genetically organized to meet the trials of life: survival, growth
and reproduction. LH theory has also predicted (and found) a general factor of personality
(GFP), and the evidence for this is now substantial. One outstanding issue is whether
the GFP is related to the g factor of cognitive ability. There is reason going back
to Spearman (1932; e.g., the work of Webb, 1915) to believe they are related. In this
paper, we test this possibility using data from the Vietnam Experience Study which
randomly sampled 4,462 Vietnam war veterans from a total sample of about five million
Vietnam era army veterans. Exclusionary criteria included passing a fitness test,
and achieving a final rank of no higher than sergeant, but otherwise the sample is
representative of the US male population for the period 1965-1971.We applied hierarchical
confirmatory factor analysis to the Minnesota Multiphasic Personality Inventory and
15 cognitive ability tests. The MMPI yielded three first-order factors of Somatization,
Internalizing and Externalizing, while the cognitive ability measures provided a fit
to four first-order factors of Memory, Dexterity, Crystallized and Fluid intelligence.
At the apex of both measures there was a general factor and we were able to fit a
model which integrated both structures. This model provided a close fit to the data
(χ2 = 3114.1, df = 235, RMSEA = .052, SRMR = .047, NNFI = .97), and provided an estimate
of -.23 for the correlation between the GFP and g. Possible explanations for the low
correlation will be discussed including that intelligence and personality are largely
mutually exclusive reproductive strategies, the first aimed at generating resources
and the second at maximizing one’s share of resources.