The neuroscience of human intelligence differences
Deary et al., 2010
Summary
- 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
- Links: [ website ]
Background
- 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
Methods
- 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
Results
- 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
Conclusion
- 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
