Lecture 8- Nature Nurture Language Development

Question 1

What is Specific Language Impairment

Answer 1

• Communication disorder
• Present with no hearing loss or intellectual disability
• Common development disorder
• Impact persists into adulthood

Question 2

Heritability (A) =

Answer 2

2(rMZ - rDZ)

Question 3

Shared environment (C) =

Answer 3

rMZ - h2

Question 4

Non- shared environment (E) =

Answer 4

1 - rMZ

Question 5

Components of Phenotypic variation (P) =

Answer 5

P = A+C+E

Question 6

What are the limitations of a twin study when studying language ability

Answer 6

• Large sample required
• It can be difficult to identify twins
• Language phenotypes are often limited and lack metrics interpretable for comparison
• Possible twinning effect

Question 7

At age 2 twins have higher or lower average language score compared to age norms

Answer 7

Lower

Question 8

Zygosity effect on language ability was still evident at age

Answer 8

4 but resolved by 6

Question 9

The gap in language ability is more pronounced in

Answer 9

• MZ twins then for DZ twins

- Boys more than girls

Question 10

At age2, statistically significant heritability was found for

Answer 10

Vocabulary (26%)

Grammar (52% boys, 43% girls)

Question 11

At age 4, the heritability estimates were

Answer 11

Considerably high and increased by age 6

Question 12

Convergent evidence for moderate to high heritability was obtained at age

Answer 12

16

Question 13

Language ability is not 100%

Answer 13

Heritable

Question 14

Twinning effect elevated risk of

Answer 14

SLI at both ages 4 and 6

Question 15

At age 4 the heritability estimates were higher for

Answer 15

SLI group than for the total sample and increased with age

Question 16

The overall pattern of heritability was different for

Answer 16

NLI