Developmental psychology
Chapter 3
The nature-nurture debate

Introduction

Precocial and altricial species

Precocial species: they young are physically mobile and able from the moment of birth or hatching.
Altricial species: are helpless and do not have this capacity at birth.

Nativism and empiricism

Nativism: the view that many skills or abilities are ‘native’ or hard wired into the brain at birth, the result of genetic inheritance.
Empiricism: the view that humans are not born with built-in ‘core-knowledge’ or mental content and that all knowledge results form learning and experience.

Cognitive development

Cognition: mental activity.

Mental age and intelligence quotient (IQ)

Chronological age (CA): a person’s actual age
Mental age (MA): an individual’s level of mental ability relative to others.
Intelligence quotient (IQ): a measure of a person’s level of intelligence compared to a population of individuals of approximately the same age.
Originally (MA/CA)*100

Intelligence tests

Four important notes about IQ:

• The simple MA/CA*100 is no longer used
• The average IQ given is always 100. tests are always standardized once a few years.
• Children’s and adult’s raw scores tend to increase from one generation to the next.
• The items on IQ tests invariably proceed from the simple to the complex, so that an individuals raw score is derived from the number of items passed before they make mistakes.

What is intelligence, on ability or several?

To a large extent how intelligence is defined determiners how it is measured.
There are those who argue that a general intelligence ability underlies performance on all intelligence tests.
Others suggest that intelligence is made up of a number of specific abilities or subskills.
Still others have argued that performance on intelligence tests is unrelated to our ability to ‘live our lives intelligently’.

Intelligence test items

Many test divide intelligence into two broad abilities.

Verbal subscales

Similarities: the child is asked in what way things might be similar.
Comprehension: measures the child’s common sense and understanding.
Recall of digits

Performance subscales

Block design: This child is given a set of blocks with colored patterns on them, and asked to use them to make patterns that the tester knows.
Copying: the child is shown a drawing and asked to copy it on a sheet of paper. The drawings are initially simple and become progressively more complex geometric shapes.

Controversies and issues in intelligence

Heriability: a statistical measure that describes how much of the variation of a trait in a population is due to genetic differences in that population.

Heritability

Heritability estimates refer to a population, and tells us nothing about individuals.
Also depend on the range of the environments in the population that is studied. (if the environment is fairly uniform than heritability may be high, but if environmental differences are large then heritability may be low).

Heritability estimates

Genetic determinism: the hypothesis that people become who they are as a consequence of their genetic inheritance.
Environmentalism: the hypothesis that people become who they are as a consequence of the learning and experiences they have had throughout life.

There is a highly complex interplay between factors.

Genetic contributions to cognitive growth

Familial resemblance

Familiar resemblance: the resemblance between relatives whose genetic relationship to each other is known.

Missing heritability

Missing heritability: the failure to find any of the genes associated with cognitive abilities.

Nevertheless it is commonly agreed that intelligence has a strong genetic component and it is thought that its heritability increases with individual’s age.

Gene X environment interaction (G x E)

All development results from the interaction of both genetic and environmental factors.
A gene X environment interaction is when different genotypes respond to similar environmental factors in different ways to create a individual’s phenotype.

Phenylketonuria (PKU): a rage genetic mutation which, if left untreated, results in severe mental retardation and learning difficulties.

Chronic obstructive pulmonary disease (COPD): a collection of lung disorders such as emphysema and bronchitis and airflow obstruction. People with COPD have difficulty breathing.

Environmental influences on cognitive development

Adoption studies

Skeels’ study

An early deprived upbring can have serious detrimental effects on children’s development, and these detrimental effects can be ameliorated, at least in part, by placement into good quality adoptive homes.

Romanian adoptees

Environmental drift: changes in developmental functions that result from, and are in the direction of changing environments.

Internationally adopted children are developing well considering the preadoption adversity to which many of them have been exposed. But the extend of the developmental recovery is related to the age at which they are adopted.

Other adoption studies.

Cognitive development is not largely under genetic control.

The Flynn effect

The Flynn effect: an increase in the average intelligence quotient (IQ) test scores over generations.
Possible causes:

• A reduction in family size so that the children get more parental input
• Improvements in education
• Improvements in diet
• The increasing complexities of modern societies which include complex technological inventions.

The Flynn effect is reducing in first world countries and cannot be attributed to genetic causes (genetic changes take many generations to have an effect).

Raven’s progressive matrices (RPM): a culture-free non-verbal intelligence test which items arranged in order of difficulty.

Compensatory education

Poverty and malnutrition

Malnutrition: a serious condition that occurs when a person’s diet does not contain the right amount of nutrients.

Poverty and malnutrition can have a devastating negative effect on children’s development. It affects brain development and cognitive functions.

Head start and sure start

The longer children live in poverty, the greater their academic deficits.

Head start

Began in the USA in 1965
Its aim: to help break the cycle of poverty of low-income children from birth to age 5.

Sure start

the UK equivalent of head start.