Studies investigating evolutionary theories on the origins of national differences in intelligence have been criticized on the basis that both national cognitive ability measures and supposedly evolutionarily informative proxies (such as latitude and climate) are confounded with general developmental status. In this study 14 Y chromosomal…

This study investigated whether a unitary elemental process or several independent processes underlie psychometric "g" (factor of general intelligence). Results with 101 college students administered 2 intelligence tests and a large battery of elementary cognitive tasks suggest that as many as 4 independent components make up…

Because they used an inappropriate statistical procedure, J. H. Kranzler and A. R. Jensen (1991) have not demonstrated that a factor of general intelligence ("g") depends on several independent factors. A factorial reanalysis of their data suggests that speed and efficiency of information processing are important in "g." (SLD)

The hypothetical idea of a perfectly pure psychometric "g" is empirically unattainable. Because the unity of "g" cannot be proved or disproved by factor analysis, the unitary "g" hypothesis represents a parsimonious assumption. J. B. Carroll's (1991) analysis demonstrates the relationship between psychometric and…

In their reply to the present author's critique (1991), J. H. Kranzler and A. R. Jensen have still not demonstrated that a factor of general intelligence, "g," depends on, or contains, several independent factors. They have only demonstrated that an estimate of "g" is predictable from several independent components. (SLD)

Longstreth's critique of Jensen's research on the relationship of IQ to individual differences in visual reaction time (RT), measured in the Hick paradigm, is said to have numerous errors of fact and interpretation, some trivial and some of theoretical importance. (Author/LMO)

Two experiments with 172 undergraduate students (70 males and 102 females) examined the relationship among spatial, imagery, and verbal ability and the multitrial free recall of brief prose passages. Results suggest that the psychological mechanisms underlying prose learning performance clearly differ depending on the ability being examined. (SLD)