Differential Psychology
e.g. Galton, Spearman idea of single factor; general intelligence or g speculation
· Found positive manifold in Binet-type tests too
· Different types of intelligence described as `hotchpot' with no theory
e.g. Thurstone, Guilford, Sternberg, Gardner · Thought g was a type of mental (physiological) energy
· Ability tests since then all correlate positively
Spearman tended to be right, everyone who came
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