Intelligence and Cognition: Neurobiology of Intelligence

Review of Last Lecture

  • Matrix Reasoning Task:
    • Taken from an article, implementation available in Guerilla (online experiment software). Correct answer is the third option.
  • Figure Weights Task:
    • Two triangles equal one square. Three triangles equal three squares, representing six triangles, with the ball remaining as is.

Clarification on Types of Intelligence

  • Questions arose regarding emotional, social intelligence, and their relation/differences compared to general intelligence (G).
  • Intelligence definition: capability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience.
  • Emotional regulation and social ability are separate from general intelligence.
  • Terminology Difference:
    • Cognitive field: intelligence = cognitive intelligence (G factor, cognitive abilities).
    • Other fields: social intelligence = social skills (skill set).
    • Moral reasoning isn't directly measured, but social skills and emotional intelligence exist separately from the G factor.

Neurodiversity

  • Adjustments to tasks can be made for neurodiverse individuals (e.g., colorblind version of Progressive Matrices, visual/auditory versions of the digital plan).
  • WAIS-V allows skipping tasks but with limitations.
  • Tasks are often applied with minimal adjustments, potentially disadvantaging neurodiverse individuals and requiring score interpretation differences.

Studies on Neurodiversity and Intelligence

  • Newcastle University meta-analysis:
    • Examined data from 1800 neurodivergent individuals on WAIS/WISC.
    • Autistic individuals: verbal and non-verbal reasoning within typical range, processing speed one standard deviation below the mean (15 points on an intelligence scale), working memory slightly reduced.
    • ADHD individuals: mostly age-expected levels but slightly reduced working memory score.
  • Study on non/low verbal individuals with autism:
    • None could complete the WISC.
    • Some performed well on certain tasks.
    • Conclusion: minimally verbal/non-verbal autistic children may be wrongly regarded as having little cognitive potential.

Neurobiology of Intelligence

Brain Structure and Intelligence

  • Darwin (1871): brain size relative to body size in humans is closely related to higher mental powers.
  • Species with complex cognitive tasks have evolved brain size and shape to support these functions.
  • Question: Does this hold within humans (relationship between IQ and brain structure)?
  • Do smarter people have larger brains?
Early Investigations and Controversies
  • Francis Galton (Darwin's cousin):
    • Investigated individual differences in intelligence in relation to approximated brain size (head size).
    • Males with high honors degrees at Cambridge had larger heads (indicative of larger brains).
    • Strongly debated, controversial due to historical misuse, leading to racism, sexism.
Modern Perspectives and Meta-Analyses
  • Skeptical researchers:
    • Evidence not strong enough to accept a simple correlation between intelligence and cranial capacity.
    • Even if true, brain size accounts for a negligible percentage of variation in intelligence.
  • 2005 meta-analysis:
    • Brain volume-IQ correlation in females, males, adults, and children.
    • Effect size is small but consistent across tissue types.
  • 2015 review (published and unpublished studies, >8000 individuals):
    • Significant positive correlation between brain volume and IQ.
    • Generalized over age groups and sex.
    • Evidence of strong publication bias (positive correlations more likely to be published).
    • Strength of association overestimated in literature.
Correlation Between the Number of Brain Cells and IQ
  • Assumption: brain size/volume equals more brain cells.
  • Study by (Author's name not provided):
    • Investigated correlation between number of brain cells and IQ using post-mortem brains from Danish males.
    • No correlation between IQ and number of brain cells.
    • Weak correlation between IQ and brain weight (replicating previous findings).
    • Near-zero correlations between other measures (white matter volume, grey matter volume, etc.) and IQ.
    • Number of glial cells also showed no relation with IQ.
    • No evidence of people with larger brains, more brain volume, or heavier brains having more neurons and therefore having a higher IQ.
Sex Differences and IQ
  • Male brains (on average): 10-11% larger total brain volume than women.
  • Clear absence of sex differences in IQ.
  • Larger brains do not necessarily translate into higher IQ in humans.
Grey Matter Volume
  • Non-linear increase.
  • Men: greater grey matter volume in blue locations.
  • Women: greater grey matter volume in red areas.
  • Structural differences between men and women lead to differences in, for example and strategies or functions of the brain that underlie these sex differences in volume.
Another study mapping Male and Female Brains
  • For men
    • Posterior sensory integration areas correlate with intelligence scores in those areas.
  • For women
    • Inferior frontal areas (language processing) correlate with Intelligence Scores.
Nature vs. Nurture Debate
  • White matter volume can change due to learning new skills (juggling).
  • Nurture element to brain structure.
Knowledge Test in London
  • Test of London's backstreets and landmarks.
  • Trainees memorize routes, covering 25,000 streets and 20,000 landmarks.
  • Only one in five attempts for this knowledge test is successful.
  • Hippocampus (spatial navigation) of London cab drivers significantly larger than in rest of population.
Follow-Up Test
  • Examined the impact of longitudinal impact on test takers.
  • Compared the two variables of qualified trainees, non-qualified trainees, and the controls.
  • Qualified trainees, higher and the study the data, were able to improve the gray matter for their test.

Environmental Factors

  • Differences between males and females, may be partly innate, but that may also be some life and environment experiences.
  • Practicing juggling or becoming a London cabbie changes brain structure.
Perceptual Reasoning
  • Sea Hero Quest App
    • Sea Hero quest app is a spatial navigation task.
    • Men outperformed women in this type of task.
GDP Per Capita
  • Countries, such as Finland, the US, Canada, and other western countries, all performed very well
  • Countries such as Egypt, India, and Iraq all perform below.
  • What is seeing? a race effect or a country wealth effect?
  • Wealthier countries show a higher performance, according to this application and test.
Gender Index
  • GDP correlates with with women's performance on this task with the gender gap decreasing.
  • Gender gap is smaller for people that live in countries where they more opportunities.
Brain Structure Summary
  • There is a strong small correlation between brain volume and IQ
  • The differences do not transfer over to the overall differences in IQ.
  • Consistent gender effect is strongly related to environmental equality.

Relationship Between IQ and Brain Function

Neural Efficiency Theory

  • Some people have more efficient brains than others.
  • More intelligent people require less brain activity to do the same task successfully.
Ravens Matrices
  • Glucose metabolic rate correlated with the Ravens Matrices score.
  • Scores of a higher metabolic rate equals a lower performance in IQ, and vis versa.
Post Tetris Study
  • Cerebro metabolism decreased.
  • Higher IQs are directly correlated to this study.
  • This means, being to train to efficiently to use brains.
Additional Study of Males and Female's Spatial Awareness
  • Male Participants showed a significant correlation between score and brain efficiency in the temporal lobes of both sides.
  • The plot is in the opposite direction.
  • It was found that female participants had no correlation to the study.
Correlations and Efficiency in Recent Years
  • Compared the gray and white matter between males an females.
  • With IQ with males they could find no correlation.
  • And those of that, with the female and other variables, was able to correlate IQ.
  • Brains need to be able locked down what the IQ is at this point.
  • Suggested the differences between males and females.

New Neuroscience of Intelligence

  • Not all brains work in the same way
  • Individuals scan show functional connectivity.
  • And so on each subject to uniquely change the way their cognitive function will work.
  • Stable, but unique individual.
  • Functional networking happens within frontal and parietal networking.
  • These are what they believe to be the fingerprints for humans and how they can tell people apart.
  • Functional abilities are often seen in the same area and how stable of time passes.