PsyD 627 Midterm

Fall 2025

Galton

First to study individual differences in intelligence

Believed intelligence inherited , could be measured using tests and was related to sensory abilities

Binet and Simon

Developed first modern IQ test to ID school kids needing support

Introduced the idea of mental age (mental ability as compared to peers)

Spearman

General intelligence (g) and specific factors (s) for particular tasks - single underlying intelligence influences all cognitive tasks 

Thurstone 

Primary Mental Abilities 

rejected g, argued intelligence is made of several independent abilities like verbal, numerical, spatial , memory , word fluency 

Carroll

Three Stratum Theory (broad to narrow)
III - general intelligence g
II - broad abilities (Gf, Gc, memory, processing speed, visual/spatial
I- narrow specific skills

Cattell

Fluid and Crystallized Intelligence
Fluid (Gf) = problem solving, novel reasoning, independent learning

Crystallized (Gc)= aquired knoweldge, experience, education

Horn 

Added additional elements to Cattell’s theory like long-term retrieval and processing speed 

CHC

g at the top and then 10 broad in the middle, dozens of narrow abilities at the bottom

gold standard of understanding and measuring intelligence 

III g 

II Broad including crystallized, visual spatial, quantatative, etc.

I- 70+  under each broader category