Human Intelligence
'General Intelligence,' Objectively Determined and Measured
Charles Spearman · 1904 · American Journal of Psychology
Proposed the existence of a general intelligence factor (g) underlying performance across cognitive tasks.
Research objective
Investigate whether diverse cognitive abilities share a common underlying factor.
Methodology
Used factor-analytic techniques on test scores across multiple cognitive domains, examining their intercorrelations.
Key findings
- All cognitive tests correlate positively (the 'positive manifold').
- A single general factor (g) accounts for most shared variance.
- Specific abilities (s) account for task-specific performance.
Strengths
- Mathematically formalized intelligence research.
- Remarkably durable - g remains one of psychology's most replicated findings.
Limitations
- Does not capture all human cognitive variation.
- Often misinterpreted as a fixed biological essence.
Practical implications
- Foundation of psychometrics and IQ testing.
- Still central to debates about intelligence theory and education.
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