1. Developmental psychology: Syllabus guide
Nature/nurture debate in relation to the development of intelligence as measured by IQ
Twin studies
Adoption studies.

2. Nature vs. nurture debate: origins
The “nature vs nurture debate” has its origins in the quest to define and measure intelligence.
Inherited from parents or determined by environment?
In particular, our upbringing & schooling?
Intelligence is difficult to ascertain since we cannot directly observe it but have to infer it from the way in which people behave.

3. Spearman & Wechsler
Spearman suggested there was a single factor of general intelligence (the ‘g’ factor) ie an inherited single factor responsible for all intellectual functioning.
Wechsler developed the most commonly used intelligence tests

4. Binet & Simon
Binet and Simon developed tests and scales at which “normal children” aged between 3 and 13 would pass.
They developed the term “mental age” – the age at which most children in an age group passed all but one of the items for that test.
In this way they could compare the general intelligence levels of all children.
Example:
A 7 year old who passes a test designed for 8 year olds would therefore have a mental age of 8.

5. Intelligence Quotient (IQ)
In 1916 the Stanford-Binet Scale introduced the idea of the IQ score. This is originally calculated by dividing mental age by chronological age and multiplying by 100.
Thus an adolescent of a chronological age of 15 years with a mental age of 15 years would have an IQ of 100 – this is described as an average IQ score.

6. Nature vs nurture
Both nature & nurture have a part to play in the development of intelligence.
Psychologists generally believe that heredity (nature) plays a role in intelligence but the environment (nurture), especially schooling, affects it.
The genetic component is fixed at birth, while the environment supports, encourages and teaches children to reach their potential.
Improving the educational & social conditions for children is one of the best ways intelligence can be increased.

7. Most supporting evidence comes from
TWIN STUDIES & ADOPTION STUDIES (McGue et al. 1993)
Environmental & Genetic Factors affecting Intelligence – 4 minutes
Genetics & Intelligence – 3 minutes
Racial differences in IQ scores – 5 minutes
Identical twins separated at birth – 9 minutes

8. Culture & IQ The debate on cultural differences in IQ are linked to:
Diversity in the population and
Ethnic differences noted in performance on IQ tests.
This has led to serious racial disputes about group differences in average IQ’s in the US.

9. Culture & IQ Recent research has shown that:
Differences between cultures in IQ are not noted in very young children.
The differences start after children begin school. Thus ‘nurture’ (environment) plays important role.
Cultural differences can be seen in the importance of schooling in Japan ... Explain. (May have nothing to do with genetics)
Another group difference is the apparent increase in IQ over time... Explain. (Increased educational opportunities account for improvements)