1. Individual Differences and Group Differences in Intelligence

2. Some questions to think about …
What accounts for how intelligent you are?

3. Some questions to think about …
Is there something about your race, gender, family background or culture that contributes to your intelligence?
or takes away from it?

4. Some questions to think about …
What are the roles of Nature & Nurture?

5. Some questions to think about …
What are the roles of Nature & Nurture?
First, we will look at factors that influence the result of intelligence testing of individuals
then
factors that influence intelligence testing of groups.

6. Intelligence Testing of Individuals
Evidence for genetics
Heritability: the proportion of variation that is attributed to genes
Estimates of the heritability of intelligence range from 50 to 80 percent
Identical twins exhibit similarity in talents such as music, math, and sports.

7. Intelligence Testing of Individuals

8. Intelligence Testing of Individuals
Evidence for genetics
Adoption studies:
Intelligence scores of adopted children with their adoptive parents correlate mildly during childhood
However in adulthood, correlations approach zero.

9. Intelligence Testing of Individuals
Evidence for genetics
Adoption studies:
Intelligence scores of adopted children with their adoptive parents correlate mildly during childhood
However in adulthood, correlations approach zero.
Adoption enhances intelligence scores of mistreated or neglected children

10. Intelligence Testing of Individuals
Evidence for environment
Hunt’s observation of destitute Iranian orphans
Couldn’t sit up at age 2 or walk at age 4.
Delayed development of
Romanian orphans
With enrichment, significant
gains were made
Head Start programs in U.S.
(aptitude benefits diminish over time)

11. Intelligence Testing of Individuals
Conclusions:
Genetic influences are particularly evident as people age.
Environmental influences especially noticeable in young children
Early “enhancement” programs of normal infants don’t yield long-term intelligence differences
Genetics and environment work together – it’s not either/or

12. Intelligence Testing of Groups

13. Intelligence Testing of Groups
What differences are there in mental ability scores between male & female?
Females are better spellers, more verbal, better at locating objects, detecting emotions and more sensitive to color, touch and taste.
Males outperform females in spatial ability, complex math problems.
Both score about the same in math computation and overall math performance.

14. Intelligence Testing of Groups
Reasons for these differences may be evolutionary or because of experience. (Nature or Nurture?)
Experience does matter
Playing action video games enhance spatial abilities

15. Intelligence Testing of Groups
Reasons for these differences may be evolutionary or because of experience. (Nature or Nurture?)
Culturally-based social influences matter
Gender-equal –vs- gender-unequal societies

16. Intelligence Testing of Groups
Racial & Ethnic Similarities & Differences
There are many group differences in average intelligence scores.
European & Maori New Zealanders
Israeli & Arab Jewish people
Hearing & deaf people
Group differences are not a basis for judging individuals
Women outlive men by 4 years, but that doesn’t say how long you will live

17. Racial & Ethnic Similarities & Differences
Heritability contributes to individual differences, but group differences may be entirely environmental
Deaf –vs– hearing given an intelligence test rooted in language skills, who would do better?
Genetic differences between three Icelandic villagers or between three Kenyans will exceed that of the differences between the two groups

18. Racial & Ethnic Similarities & Differences
The differences between these three people
the differences between these three people or
Is greater than the differences between the two groups of people

19. Which of 1-5 would go in the blank square?
Which is different from the other four?
Which of 1-5 would go in the blank square?
Example shows a dot in a circle below the line.
Which 1-5 could you do that with?

20. Racial & Ethnic Similarities & Differences
So differences in intelligence test scores between groups is based on differences in the environments
Wealth gap differences
Schools & culture differences
Differences in the era

21. Final item: Expectations
Attitude and expectations can affect intelligence testing.
Math test to equally capable men & women, but women were told females do not do as well had lower scores
Stereotype threat a self-confirming concern that one will be evaluated based on a negative stereotype.

22. Final item: Expectations
Negatively stereotyped minorities and women may have unrealized academic potential.
Women have scored higher on math tests when no males are present
African-Americans have scored higher when proctor is African-American rather than Caucasian.
Minority students who were challenged to believe in their potential produced higher grades and had lower dropout rate.

23. Final item: Expectations
Life’s great achievements result not only from “can do” abilities,
but also from “will do” motivation.
Competence + Diligence
brings
Accomplishment