5. Lewis Terman &Alfred Binet
In the US, Lewis Terman
adapted Binet’s test for
American school children and
named the test the Stanford-
Binet Test. The following is the
formula of Intelligence Quotient
(IQ), introduced by William
Stern:
6. Measuring Intelligence
At any age, children who are average will have an IQ
of 100 because their mental age equals their chronological
age.
Two-thirds of children will have an IQ score between 85 and 115
Approximately 95% will have scores between 70 and 130
8. GENETICS
For more than a century , researchers have been studying that
how much genetic legacy influences our intelligence.
Finally they determined that our genes influence our intelligence
and IQ by 40-80%
9. 9
Genetic Influences
Studies of twins, family members, and adopted
children together support the idea that there is a
significant genetic contribution to intelligence.
10. 10
Environmental Influences
Studies of twins and adopted children also show
the following:
1. Fraternal twins raised together tend to show
similarity in intelligence scores.
2. Identical twins raised apart show slightly less
similarity in their intelligence scores.
11. Why do Japanese and Chinese students
perform better than Americans on
intelligence and achievement tests?
They score the same before school but once school starts they begin to show more
gains. This due to:
Spending more time in school
More time doing homework
Pressure and support from parents to achieve academically
12. 12
Racial (Group) Differences
If we look at racial differences, white Americans
score higher in average intelligence than black
Americans (Avery and others, 1994).
White-Americans Black-Americans
Average IQ = 100 Average IQ = 85
Hispanic Americans
13. 13
Environmental Effects
Differences in intelligence among these groups are
largely environmental, as if one environment is
more fertile in developing these abilities than the
other.
