Medicine & USMLE

Theory of General Intelligence

  1. Theory of General Intelligence
  2. Fluid Intelligence
  3. Crystallized Intelligence
  4. Theory of Multiple Intelligences
  5. Triarchical Intelligence Theory
  6. Primary Mental Abilities


The Theory of General Intelligence proposes that there is only one intelligence, measured by a single ‘g factor’ that underlies performance in all cognitive domains. Performance in different cognitive tasks are interrelated, all hinging on the single ‘g factor’.

Key Points

  • Theory of General Intelligence
    • Single g factor underlies performance in all cognitive domains 
      • The psychologist Raymond Cattell further split general intelligence into Fluid Intelligence and Crystallized Intelligence
      • Intelligence is interrelated
        • high scores in one area are correlated with high scores in others 
    • Proposed by Charles Spearman


According to this theory, a girl who is good at math will be just as good at spelling, geography, interpersonal skills, and basically any other task that requires thinking. That is because her performance in all these areas is dependent on one, single g-factor.