The neuroscience of human intelligence differences

Deary et al., 2010


  • What does neuroscience reveal about the biological bases of human intelligence differences?
  • Genetic studies identified additive genetic contributions to aspects of cognitive ability
  • Brain-imaging studies identified differences in brain pathways that contribute to intelligence differences
  • Efficiency may also correlate positively with intelligence
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  • Differential psychology investigates how individuals vary along mental continua, while differential neuroscience focuses on the biological bases
  • Intelligence differences roughly follow a normal distribution in the population
    • Males have a slightly wider distribution than females at both ends
  • Differences in intelligence are quite stable in rank order throughout development
  • g factor accounts for approximately 40% of total variance across a variety of cognitive tasks


  • Neuroscience of intelligence must explain the following established facts about cognitive test performance:
    • About half the variance across cognitive tasks is contained within general cognitive ability
    • Much less variance is contained within broad domains of capability
    • There are distinct ageing patterns for fluid and crystallized intelligence


  • Genetics affect many brain structures and functioning acting as endophenotypes for intelligence
  • Morphological changes during brain development in childhood is under some form of genetic control
  • Current evidence there is a moderate positive correlation between brain volume and intelligence
    • Slightly higher correlation between intelligence and overall grey matter compared to white matter
  • Intelligence seems best described as a small-world network
  • Male seems to be more neuronally efficient during spatial cognitive tasks, whereas females are more efficient during verbal tasks
    • Consistent with established sex differences in performance on these tasks
  • Males and females achieve similar levels of general intelligence with differently structured brains


  • Intelligence involves both figuring things out and applying what’s been figured out in the past
  • People not only differ in general cognitive ability, but also in how they achieve that performance given differently structured brains
Elias Z. Wang
Elias Z. Wang
AI Researcher | PhD Candidate