Intelligence

Intelligence

1. What does intelligence mean?

   • IQ tests give the suggestion for someones intelligence
     • If you define being intelligent as being highly skilled

2. Charles Spearman

   • studied relationships between cognitive factors , a constant correlation between in unrelated subjects
     • mental ability understood as a single general factor
       • Developed by Carroll(1993)
         • Three stratum model
           • one= 70 narrow abilities
             • two= gathered these into several broad ability factors
               • overarched by one g factor

3. Biological factors

   • Sex difference, neural anatomy and hormones
     • Halpern (1997)
       • difference in cognitive abilities between the two sexes
         • Women= higher verbal fluency
         • Men= higher mental rotation and scientific reasoning
     • Haier et al (2005)
       • used MRI scans (already obtained) = ethical
         • Men have more grey matter in their frontal and parietal lobe
           • associated with motor skills and reasoning
       • Women have increased grey matter in different areas of their frontal lobe and Broca's area (important for speech and writing)
     • Van Goozen et al (1995)
       • study of female-male transexuals given testosterone prior to sex-change
         • significant increase in visual-spatial awareness and lower scores on verbal fluency.
           • Reversed for males

4. Genetic factors

   • Heredity factors often use twin or adoption study methods
   • Scarr and Weinburg(1978)
     • comparison of intellectual abilities of parents and their biological and adoptive children.
       • Stronger correlation between biological
   • Plomin& Defries (1998)
     • compared monozygotic and dizygotic twins
       • measures of spatial and verbal skill
       • testing their test scores, despite their shared environment
       • issue with MZ and DZ twins is that they assume that parents phenotype are uncorrelated
         • do not consider assertive mating or interaction between genes and the envrionment
   • No individual gene found or combination with significant influence
   • results have been hard to replicate

5. Application

   • IQ tests
     • Fluid skills
     • Crystallised skills
     • An effective test= valid and reliable
       • Face validity
         • concurrent validity
           • compare one test to another
             • Raven and Wechsler
               • Raven test- missing item- fluid skills
               • if you score highly on one you should score highly on the other
           • split-half reliability
             • checking the consistency of the intelligence test using similar questions
             • Avoid ceiling and floor effects
               • should not get 100% or 0%
       • Test- rettest relaibility
       • They should avoid bias
         • could have issues with language and cultural issues
         • (see Gould)
     • Ethically right to give labels?

6. Van Leeuwen, M.

   • Aim- researchers wanted to separate shared genetics from shared environment effects on intelligence. They Aimed the relative influence of assortative mating, cultural transmission, and GE interaction and GE correlation. They also wanted to investigate why spouses have similar intelligence scores.
     • Method
       • Sample
         • Drawn from the Netherlands Twin Registry, all over Holland
         • 214 families of twins about to turn 9 years old
           • also had a extra sibling aged between 9 and 14
           • 112 families agreed to participate
             • mean age of twins= 9.1
             • mean age of siblings=11.9
             • mean age of mothers and fathers= 41.0 and 43.7
         • only families with children without self-reported psychiatric problems, major medical issues, special educational needs or physical or sensory disabilities were included
       • Design and procedure
         • consent to participate in the study and compensated for travel.
         • Children were given a present for taking part.
         • Families completed a questionnaire or DNA cheek swabs at home prior to the study to confirm zygotsity
           • Children completed a Raven's standard progressive matrices in separate rooms
             • verbal instructions
       • Compared intelligence of MZ and DZ twins, siblings and parents