Genetic & Environmental Influences on Intelligence

Genetic & Environmental Influences on Intelligence

1. Definitions of Intelligence

   • Recent Advances
     • Gardner's Theory of Multiple Intelligence
       • Linguistic, Logico-mathematical, Musical, Spatial, Bodily-kinesthetic, Naturalistic, Interpersonal, Intrapersonal.
         • Unique biological basis, distinct course of dev. and endstates. Education required to change raw potential.
           • Genetics and Environment responsible

2. Ethnic & Socioeconomic Variations

   • Why does it appear that low SES groups heavily represented at the low end of the IQ scale?
     • Responsible for the IQ nature-nurture debate
       • Does heredity vary with SES and enthicity?
         • Do certain groups have fewer opportunities to acquire skills for successful test performance?
   • Arthur Jensen
     • Heredity largely responsible for individual, ethnic and SES differeces in IQ
       • Huge debates: spurred further research and ethical questions
         • Herrnstein & Murray: The Bell Curve study

3. Genetic Variations

   • Heritability
     • Greater the genetic similarity, the greater the resemblance in IQ
     • No question: heredity partially responsible for IQ
     • What role does niche picking have on studies?
     • Environment plays a role: similarities in IQ are higher when environment has been the same
     • Cannot be used to prove Jensen's theory
     • Lower SES conditions affect IQ as children are prevented from attaining genetic potential
   • Adoption Studies
     • Adopted children: caring environment increases IQ
     • Studies show that as children grow, IQ resembles biological relatives'
   • Race & Ethnicity
     • Wide genetic variation within races; minimal genetic variation between them.
     • 'Race' not a good descriptor: many racial designations encompass large cultural, linguistic & bioloical diversity.
       • Danger: We cannot perpetuate idea that some groups are inferior in IQ
   • Cultural Bias
     • Are cultural differences in IQ due to genetics or test bias?
       • NO: reflects common culture. Fair to both advantaged and disadvantaged groups
       • YES: Not all children have had opportuity to learn certain knowledge/ skills needed for testing.
         • Lack of exposure to certain communication styles/knowledge + negative stereotypes regarding ethnic group can undermine childrens' performance.

4. Environmental Influences

   • Shared Environmental Influences
     • Observations of Home Environmental Qualities
       • Stimulations provided by caregivers: moderately linked to mental dev.
         • Caregivers' talk to infants contributes strongly to early language progress and primary school achievement.
           • *Caution: Biological parents with high IQ may provide better stimulation & have children with higher IQ: genetic-environmental correlation.
     • Family beliefs about Intellectual Success
       • Immigrant parents' beliefs that education is a gateway to success plays a profound role
       • Parents' expectations for educational attainment: linked to success in school.
         • Warm, appropriately demanding child rearing, cognitively stimulating parent-child activities & parental involvement.
     • Pervade the general atmosphere of the home & similarly affect siblings.
   • Nonshared Environmental Influences
     • Make siblings different to each other
       • Favouritism or assigning specific roles
     • More powerful influence on IQ than shared influences
   • Early intervention
     • Many long term benefits of early intervention, children less likely to need special education and lasting benefits in attitudes & motivation