How would you measure brain size?
What are the problems with IQ tests? Do they measure intelligence?
Why does brain size or
intelligence vary?
Do twin studies support the nature or nurture side of the argument? How?
Use your opposite hand to write....
Nature or Nurture
Rushton 1997
- Measured head circumferences and IQs of 50,000 American children.
- Asian Americans had larger heads than white children and black children.
- The larger the cranial volume, the higher the IQ scores.
Abused and neglected children have permanent physical damage to the brain.
Nature or nurture?
Gratiolet 1861
The skulls of Mexican indians
were much larger than others
Does this mean they are
more intelligent?
Does brain size matter?
Tan et al (1999) found a stronger correlation of 0.40 between brain size and IQ - using and Turkish participants
Frances Galton (1888) found students
with higher grades had bigger skulls
Modern techniques can look at brain
size in living organsms rather than
dead ones.
86% concordance rate with identical twins
even if seperated.
Genes are strong influence on IQ
Using MRI scans Ngyuyen and McDaniel (2000) found the correlation between brain size and intelligence stronger in living participants (in vivo) rather than dead ones.
Twins
Neglect seems to decrease the size of fibres that link hemispheres.
McGuire (2000)
Taxi drivers have a larger hippocampus - the area of the brain responsible for navigation.
Pascual-Leone 1995
Piano playing inreased the size
of specific regions of the brain