nature and nurture of temperament

What is temperament?

Individual differences in emotion, activity, and attention present from infancy.

What are the three temperament types in Thomas and Chess’s approach?

Easy, difficult, and slow-to-warm-up.

What traits are included in Rothbart’s within-person approach?

Fear, anger, attention span, activity level, and smiling/laughter.

What does the nature versus nurture debate ask?

Why children differ from one another.

What does “nature” refer to?

Genetic influences.

What does “nurture” refer to?

Environmental influences.

Why can’t biological family studies separate nature and nurture?

Parents provide both genes and environment.

What is genotype?

A person’s genetic makeup.

What are the two main genetically informative research designs?

Twin studies and adoption studies.

What does the adoption design compare?

Biological parents, adoptive parents, and adopted children.

How genetically related are birth parents and adopted children?

50% related.

How genetically related are adoptive parents and adopted children?

0% related.

What does similarity between adoptive parents and adopted children suggest?

Environmental influences.

What does similarity between birth parents and adopted children suggest?

Genetic influences.

What is one limitation of adoption studies?

Adoptees are often placed in low-risk homes.

What does the twin design compare?

Similarity between monozygotic (MZ) and dizygotic (DZ) twins.

How much genetic material do MZ twins share?

About 100%.

How much genetic material do DZ twins share?

About 50%.

Why are MZ twins useful for studying genetics?

They share all their genes.

What is twin resemblance measured with?

A correlation coefficient (r).

If a trait is entirely due to nurture, how similar would MZ and DZ twins be?

Equally similar.

If a trait is entirely due to nature, which twins would be more similar?

MZ twins.

Which temperament traits show strong genetic influence?

Emotionality, activity, shyness, sociability, and affect.

What is the equal environments assumption?

The idea that MZ and DZ twins experience similarly equal environments.

What is heritability?

The proportion of variation in a population caused by genetic differences.

What formula estimates heritability?

2(rMZ – rDZ).

What was the heritability estimate for extraversion in the lecture example?

64%.

Does heritability apply to individuals?

No, it applies to populations.

Can heritability estimates change?

Yes, depending on the environment and population studied.

How can parents influence child temperament?

Through genes and the home environment they create.