What is the general factor g?

g is a statistical factor capturing what different cognitive tasks share in common. People who do well on one kind of reasoning task tend to do well on others, and g summarizes that shared variance.

What’s the difference between fluid and crystallized intelligence?

Fluid intelligence (Gf) is novel problem solving independent of learned knowledge; crystallized intelligence (Gc) is acquired knowledge, vocabulary, and verbal reasoning accumulated through education and experience.

What is the CHC model?

The Cattell–Horn–Carroll framework is a hierarchical model: g at the top, broad abilities (e.g., Gf, Gc, Gv, Gwm, Gs) in the middle, and narrow, specific skills at the bottom. Many modern IQ tests are designed around CHC.

Do IQ tests measure creativity or emotional intelligence?

No. Standard IQ tests focus on specific cognitive abilities (reasoning, working memory, processing speed, verbal knowledge). Creativity, personality, motivation, and emotional intelligence are separate constructs.

Are Gardner’s and Sternberg’s theories used in scoring IQ?

They inform educational perspectives but are not the basis of mainstream IQ scoring. Modern psychometrics typically relies on g and CHC-aligned constructs when designing and interpreting tests.

Intelligence: Definitions & Theories (g, Gf/Gc, CHC, Gardner, Sternberg)

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Intelligence: Definitions & Theories

Last updated: October 9, 2025 • Reading time: ~9 min

Intelligence is the capacity to learn from experience, reason about complex ideas, and adapt effectively to new situations. In practice, it spans abstract reasoning, language understanding, working memory, processing speed, and visual–spatial skills. This guide synthesizes core models so you can read IQ reports with confidence.

Key takeaways

g summarizes what cognitive tasks share in common.
Gf (novel problem solving) and Gc (acquired knowledge) are complementary pillars.
CHC is today’s dominant framework for broad abilities (Gf, Gc, Gv, Gwm, Gs, etc.).
IQ tests sample specific cognitive abilities; they do not assess creativity, personality, or emotional intelligence.
Interpreting IQ = reading the profile and the confidence intervals, not just one number.

What do psychologists measure?

Adaptive view: intelligence is effective adaptation—spotting patterns, anticipating consequences, and choosing actions that work.

Psychometric view: intelligence is a pattern of performance across diverse tasks. Consistently stronger reasoning across domains points to higher general ability.

Functional view: how efficiently the brain encodes, maintains, and transforms information under constraints of time and attention.

The general factor g

Scores from different cognitive tasks tend to be positively correlated. Factor analysis distills that shared variance into a general factor, g. Practically, g reflects domain-general operations like maintaining and manipulating information, forming and testing rules, and controlling attention. In many IQ reports, g is expressed as the overall IQ.

Fluid vs. crystallized intelligence (Gf/Gc)

Fluid intelligence (Gf): solving novel problems independent of specific learned content—e.g., matrix reasoning, pattern discovery.

Crystallized intelligence (Gc): accumulated verbal knowledge and conceptual understanding—e.g., vocabulary, reading comprehension, general information.

Think of Gf as the engine of reasoning and Gc as the fuel tank of knowledge. Both matter for real-world performance.

The CHC framework

The Cattell–Horn–Carroll (CHC) model is a hierarchical map of abilities:

Top level: g (general intelligence).
Broad level: Gf (fluid reasoning), Gc (crystallized knowledge), Gv (visual–spatial), Gwm (working memory), Gs (processing speed), plus others (e.g., long-term retrieval).
Narrow level: specific, trainable skills (e.g., mental rotation, verbal analogies).

Modern IQ batteries are designed to sample multiple broad abilities, yielding both a global score and a strengths/weaknesses profile.

Alternative theories: Gardner & Sternberg

Multiple Intelligences (Howard Gardner)

Proposes distinct “intelligences” (linguistic, logical–mathematical, spatial, musical, bodily–kinesthetic, interpersonal, intrapersonal, naturalistic). It highlights diverse talents and learning styles.

Psychometric caveat: evidence that these are independent, testable factors is limited; many align with skills or preferences rather than separable cognitive dimensions used in IQ scoring.

Triarchic Theory (Robert Sternberg)

Separates analytical (tested in IQ), creative (novel idea generation), and practical (everyday problem solving) intelligence.

Useful for broad educational framing, but mainstream test interpretation still relies on g/CHC constructs for scoring and norms.

What IQ tests measure—and don’t

Typically measured: abstract reasoning (Gf), verbal comprehension/knowledge (Gc), working memory (Gwm), processing speed (Gs), and visual–spatial skills (Gv).

Not directly measured: creativity, personality, motivation, values, wisdom, grit, or emotional intelligence (EQ). These are separate but important for life outcomes.

Prediction and limits

Predictive strengths: IQ relates to academic achievement and some job performance—especially where learning speed and complex reasoning are central.

Limits and context: success also depends on non-cognitive traits (motivation, self-control), health, opportunity, and environment. IQ scores are estimates with error; read the confidence intervals and the profile, not just the headline number.

Mini glossary

IQ: deviation score (mean 100, SD ≈ 15) relative to age-based norms.
g: general factor summarizing shared variance across cognitive tasks.
Gf/Gc: fluid/crystallized intelligence.
Gwm/Gs/Gv: working memory / processing speed / visual–spatial ability.
CHC: hierarchical framework: g → broad abilities → narrow skills.
EQ: emotional intelligence (recognizing, regulating emotions; social competence).

Next steps

Take the main IQ test