Intelligence & Its Theories

Intelligence is the global capacity of an individual to think rationally, act purposefully, and deal effectively with the environment (Wechsler). It is the ability to learn, reason, and adapt.

Don't read this page — work through it. Each block asks you to commit to an answer before it tells you anything.

Start here: what do you already know?

Intelligence — true or false?

6 statements · 9s each

Work the IQ formula

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Key definitions

  • Stern: "Intelligence is the general ability to adjust to new situations."
  • Terman: "Intelligence is the ability to think in abstract terms."
  • Binet: intelligence involves direction, adaptation, and self-criticism.

Theories of intelligence

TheoryTheoristIdea
Unifactor / one-factorBinet, TermanIntelligence is a single ability
Two-factorSpearmang (general) + s (specific) factors
Multifactor / PMAThurstone7 Primary Mental Abilities
Group factorThurstoneAbilities cluster in groups
Multiple IntelligencesGardner8+ independent intelligences
Triarchic theorySternbergComponential, Experiential, Contextual
Structure of IntellectGuilford3-D model (operation × content × product)

Gardner's Multiple Intelligences (8): Linguistic, Logical-Mathematical, Spatial, Musical, Bodily-Kinesthetic, Interpersonal, Intrapersonal, Naturalistic.

Measuring intelligence — IQ

IQ (Intelligence Quotient) was given by Stern and popularised by Terman:

IQ = (Mental Age ÷ Chronological Age) × 100

  • Mental Age (MA) concept was given by Binet.
  • Average IQ ≈ 90–110.
IQ rangeClassification (traditional)
Above 140Genius
120–140Very superior / gifted
90–110Average / normal
70–90Below average / dull
Below 70Intellectually disabled

Types of intelligence tests

  • Individual vs Group tests.
  • Verbal vs Non-verbal / Performance tests.
  • Examples: Binet–Simon scale (first, 1905), Stanford–Binet, Wechsler scales, Raven's Progressive Matrices (non-verbal).

Explore the theories

Every one of these has been asked as a "who gave what" question. Tap through them, then use Compare on Spearman vs Gardner — the two most confused.

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Practise the IQ formula

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Exam tip: g and s factors → Spearman; Multiple Intelligences → Gardner; Triarchic → Sternberg; IQ formula → Stern; Mental Age → Binet.


Test yourself

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