Chapter 30

Factors Influencing Development of Behaviour

Maturation- WalkingIn humans, walking is a natural process that normally begins between the ages of 9 and 15 months. A newly born baby is unable to walk because his or her legs cannot support the weight of his or her body. The activities that an infant can master gradually become more complicated as the nervous system develops and the process of myelination continues. As the infant grows a genetically programmed series of events occurs which leads eventually to the ability to walk. The process is shown opposite. Progress through each stage in the sequence is called MATURATION

Maturation- Other Examples

Growth of the fetus in the uterus, development of speech and acquisition of cognitive abilities (e.g. reasoning) are all examples of maturation.

Learning is thought to be influenced by the genetic and environmental factors that affect the person.

SpeechAverage age of Infant Stage in Development of Speech

Birth-6 months Phase of crying and cooing

6-12 months Phase of babbling sounds (e.g. baba)

12-24 months Definite sounds on recognising favourite objects and persons (e.g mama)

2-3 years 2-3 word combinations(e.g. ‘where dada go?’)

3-4 years Longer more grammatical sentences (e.g. ‘what’s it for , Mummy?’)

4+ years Production of words and sentences of greater complexity as child’s thinking processes develop

Speech

• Infants only become able to proceed from one stage to the next as they grow and develop. It is pointless trying to teach a child to perform a skill if their natural maturational level for that ability has not yet been reached.

Cognitive Abilities

Cognitive Abilities

not volume. Intellectual development is also affected by environment and inherited factors.

Mass

Weight

Volume

Inheritance

Huntington’s Chorea

• Approximately 1 in 20,000 people in Britain suffer from this inherited disorder caused by a single mutant allele.

• The symptoms of this condition do not appear until the affected person is about 38 years old. This means they are likely to have had children by that point and unwittingly passed on the mutant allele to their offspring.

Huntington’s Chorea

• The condition is caused by premature death of neurones in certain regions of the brain and a decrease in neurotransmitter production. As neural degeneration continues it normally leads to:

Phenylketonuria (PKU)

Intelligence

Intelligence Testing

• What is the next number?

Intelligence Testing

Answer- 33

This test is meant to be ‘culture-fair’ in that all children being tested would be equally familiar with the idea of the numbers involved

Intelligence Testing-IQ

Cautious Interpretation of the Results

Environment –Twin Studies

If intelligence depended solely on inherited factors then identical twins would be equally intelligent whether raised together or apart.

The table opposite shows that intelligence is based on both genetic and environmental factors.

Abnormal Behaviour and Twin Studies- Alcoholism

largely from the effect of environmental factors

Schizophrenia• This condition is characterised by severe personality disorders often

involving delusions and hallucinations. Amongst dizygotic twins, if one is schizophrenic the chance of the other becoming schizophrenic is slightly greater than amongst unrelated people. Amongst monozygotic twins the chance is many times higher suggesting a major influence by genetic factors in the development of this disorder

Factors Affecting Language Development

All forms of human behaviour are influenced by inherited, maturational and environmental factors which are closely inter-related. Genes and environment influence a person’s overall phenotype.

Growing children need an environment which provides adequate support and stimulation in order to realise the full physical and intellectual potential that they have inherited in their genotype.

Growing children need an environment which provides adequate support and stimulation in order to realise the full physical and intellectual potential that they have inherited in their genotype.