Custom Search

Monday, January 31, 2011

Underlying mental traits

Underlying mental traits
The question then becomes: how many (or how few) underlying traits are there, which explain most of the difference in scores we find on a whole battery of tests? This is what psychologists hoped to find out using factor analysis – a statistical technique developed by Charles Spearman specifically for this purpose. (factor analysis a data reduction technique where relationships between a large number of variables can be reduced to a relationship among fewer hypothetical (i.e. latent) factors) Factor analysis is a complex mathematical technique for identifying how many ‘factors’ underlie a large number of individual pieces of data, and its exploration is best left to a more advanced, dedicated statistics text. However, it is relevant to mention here that two different, but equally sound, approaches to factor analysis have led to fierce debate about the number of basic elements of intelligence. The original factor solutions obtained by Spearman found a general factor of intelligence (g) and some specific factors But Louis Leon Thurstone (1938) argued that, rather than a single general intelligence, there are seven ‘separate and unique’ primary mental abilities: word fluency, number facility, verbal comprehension, perceptual speed, associative memory, spatial visualization and inductive reasoning. Horn and Cattell (1966) identified two factors, which they labelled fluid intelligence (Gf ) (fluid intelligence (Gf ) Horn and Cattell’s Gf is something akin to Spearman’s g, namely an overarching processing capacity that in turn contributes to Gc) and crystallized intelligence (crystallized intelligence (Gc) diverse skills and knowledge acquired across the lifespan) (Gc). Unlike Thurstone, Horn and Cattell believed that these different aspects of intelligence were differentially important. Gf seemed to represent something akin to Spearman’s g, namely an overarching processing capacity that in turn contributed to Gc, which represented iverse skills and knowledge acquired across the lifespan. There is some evidence to sup port this conceptualization of intelligence, as tests that tap these two different aspects of intelligence (Gf and Gc) seem to be differentially related to ageing.

No comments: