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Factor Theories of Intelligence

📊 Topic Overview​

| Papers Appeared | 9/28 (32.1%) | | Priority | 🔴 HIGH | | Coverage | Thurstone's PMA, Cattell's Gf/Gc, Vernon's model | | Often Combined With | Spearman's Two-Factor Theory |

🎯 Must-Know Concepts​

  1. Thurstone's Primary Mental Abilities (PMA) — 7 factors
  2. Cattell's Fluid (Gf) vs Crystallised (Gc) intelligence
  3. Vernon's Hierarchical Model — major and minor group factors
  4. Factor analysis — statistical method used to identify factors
  5. Comparison with Spearman — multiple factors vs single g
  6. Thurstone vs Spearman debate — is there a general factor?

Previous Year Questions​

Year-SessionQuestionMarks
2011-JuneDiscuss the factor theories of intelligence10
2015-DecemberShort note: Factor theories of intelligence3
2016-JuneExplain the factor theories of intelligence10
2017-JuneFactor theories of intelligence (B section)6
2018-JuneExplain Thurstone's Primary Mental Abilities10
2019-JuneDescribe factor theories of intelligence10
2020-DecemberShort note: Thurstone's PMA3
2021-JuneDiscuss factor theories of intelligence10

🌟 Comprehensive Answer: Factor Theories of Intelligence (~500 words)​

Introduction​

Factor theories of intelligence emerged from attempts to identify the basic dimensions of human intelligence through statistical analysis. While Spearman proposed a single general intelligence (g), later theorists argued that intelligence is composed of multiple independent or hierarchically organised factors. The primary contributors to this tradition are Louis Thurstone, Raymond Cattell, and Philip Vernon.

1. Thurstone's Primary Mental Abilities (1938)​

Louis Thurstone used factor analysis on a large battery of cognitive tests and identified 7 Primary Mental Abilities (PMA):

AbilityAbbreviationDescription
Verbal ComprehensionVUnderstanding words and meanings
Word FluencyWSpeed in producing words
NumberNArithmetical computation speed
SpaceSVisualizing objects in space
Associative MemoryMRote memory
Perceptual SpeedPQuick identification of visual patterns
Reasoning/InductionI/RIdentifying rules and relationships

Key claim: These abilities are relatively independent — a person can be high in one and low in another. This directly challenged Spearman's unitary g.

Later reconciliation: Thurstone acknowledged a higher-order factor across his PMAs, which resembled Spearman's g — suggesting g and PMAs operate at different levels of analysis.

2. Cattell's Fluid vs Crystallised Intelligence (1963)​

Raymond Cattell distinguished two forms of intelligence:

TypeDefinitionBrain BasisAge EffectExample
Fluid Intelligence (Gf)Raw reasoning ability, novel problem solvingNeurological integrityPeaks early, declines with ageLogic puzzles, matrix reasoning
Crystallised Intelligence (Gc)Accumulated knowledge and skillsExperience and cultureStable or increases with ageVocabulary, general knowledge

Cattell argued that Gf is biologically based while Gc is culturally shaped through education and experience. This distinction has been highly influential in understanding cognitive aging — people typically retain Gc even as Gf declines.

Horn (1965) extended this into the Cattell-Horn model with additional factors (short-term memory, processing speed, visual processing).

3. Vernon's Hierarchical Model (1950)​

Philip Vernon proposed a hierarchical organisation of intelligence:

g (General Factor)
├── v:ed (Verbal-Educational)
│   ├── Verbal ability
│   └── Numerical ability
└── k:m (Spatial-Mechanical)
    ├── Spatial ability
    └── Mechanical ability

This model reconciled Spearman and Thurstone: g operates at the top, with major group factors below, followed by minor group factors and specific abilities at the base.

Evaluation​

Strengths:

  • Identified specific cognitive abilities with practical value (educational assessment, vocational guidance)
  • Cattell's Gf/Gc distinction has strong empirical support and practical utility
  • Hierarchical models offer a comprehensive structure

Criticisms:

  • Factor analysis depends heavily on the tests included — different batteries yield different factors
  • Debate over whether factors reflect genuine psychological entities or statistical artefacts
  • Limited cross-cultural validity

Conclusion​

Factor theories transformed the study of intelligence from a search for a single general ability to a multi-dimensional model. Thurstone, Cattell, and Vernon collectively established that intelligence has both specific components and a unifying structure. Their work laid the foundation for modern intelligence testing and cognitive profiling, and Cattell's Gf/Gc distinction remains clinically and educationally significant.

🧠 Memory Aid​

"Three Clever Varieties" = Thurstone (7 PMA), Cattell (Gf/Gc), Vernon (hierarchy)

Cattell's Gf/Gc: "Fluid Falls, Crystal Climbs" — Fluid declines with age, Crystallised increases

📚 Related Content​

✅ Self-Assessment​

  1. What are Thurstone's 7 Primary Mental Abilities?
  2. What is the difference between fluid and crystallised intelligence?
  3. How does Vernon's model reconcile Spearman and Thurstone?
  4. Why did Thurstone's view challenge Spearman's concept of g?
  5. How does fluid intelligence change with age compared to crystallised intelligence?

💡 Exam Tips​

  • Always clarify: factor theories = Thurstone + Cattell (+ Vernon)
  • Cattell's Gf/Gc is the most likely short-note topic from this group
  • For comparison questions with Spearman: stress that Thurstone found multiple primary factors while Spearman found one general factor
  • The Gf/Gc model is essential for understanding cognitive aging