Lecture 1: Prenatal Development

Question 1

What is developmental psychology?

Answer 1

The study of change and stability over the lifespan

How we change physically, cognitively, behaviourally and socially over time due to biological, individual and environmental differences

Question 2

Outline some of the WAYS development is studied

Answer 2

Quantitative changes - easily measurable and quantifiable aspects of development e.g. physical characteristics like height and weight

Qualitative changes - changes in functions or processes such as memory, beliefs and reasoning

Stability - Not all development is change, some processes remain stable and endure throughout development e.g. temperament

Question 3

Outline some DOMAINS in which development is studied

Answer 3

Physical development - body, brain, senses, motor skills e.g. reaching and crawling

Cognitive development - learning, memory, language, reasoning

Psychosocial - personality, emotions, social relationships

Question 4

Outline some fundamental issues in developmental psychology…

(4 issues)

Answer 4

1. Individual differences -
   People develop along different trajectories
2. Sources of development -
   nature or nurture??
3. Continuity vs discontinuity -
   series of small and continuous changes? abrupt transformations? discontinuous stages?
4. Plasticity -
   open to change? when do changes have the greatest impact?

Question 5

Name 3 reasons to study developmental psychology…

Answer 5

1. Choosing social policy
2. Raising children
3. Understanding human nature

Question 6

Name the two methods for understanding change…

Explain them…

Answer 6

Cross sectional studies - studying change using children of different ages at the same time

longitudinal studies - studying change using children of the same age, and testing them repeatedly, at multiple time points as they grow older

Question 7

Name the 3 methods for understanding change…

Explain them…

(Types of studies)

Answer 7

Cross sectional studies - studying change using children of different ages at the same time

Longitudinal studies - studying change using children of the same age, and testing them repeatedly, at multiple time points as they grow older

Microgenetic studies - an extreme version of a longitudinal study where changes are examined as they occur, individual kids are tested over and over during a short space of time

Question 8

The three methods for understanding change (study types)

compare them…

Answer 8

So the three methods can tell very different stories depending on how you use them.

Say you’re studying height, if you use cross sectional or longitudinal data, they might show continuous growth
If you were to use microgenetic data, this might show discontinuous growth (measured daily or weekly) - they might grow a cm a night and then stay the same for a week)

Question 9

+/- of cross sectional studies

Answer 9

Strength - not time consuming

Weakness - cant see how individual children change

Question 10

+/- of longitudinal studies

Answer 10

Strength - can look at both individual change and across children

Weakness - time consuming, intensive to run, expensive, high drop out rates. effects of task practice

Question 11

+/- of microgenetic studies

Answer 11

Strength - precise descriptions of development

Weakness - intensive, small samples, practice effects

Question 12

How can experiments be used in developmental psychology?

Answer 12

As well as looking at change, experiments can be used to test the effect of variables on childrens’ skills or abilities

Question 13

What is preformationism?

Answer 13

The popular belief (until the 1600s) that miniature people lived in sperm and started to grow upon fertilisation of the egg

Question 14

What is epigenesis?

Answer 14

The term used to describe what we know

Question 15

What is epigenesis?

Answer 15

The term used to describe what we now know - which is that new organs and structures develop through a series of stages throughout prenatal development

Question 16

What is prenatal development?

Answer 16

Development occurring from zygote to birth

Question 17

The prenatal development stages

Stage one - Germination Stage

Answer 17

1. Germination stage (conception to 2 weeks)

On it’s journey through the fallopian tube to the womb, the fertilized egg (zygote) doubles it’s cells twice a day

Around 2 weeks post fertilisation the zygote attaches to the uterus wall and the cell becomes an embryo

Question 18

The prenatal development stages

Stage two - Embryo Stage

Answer 18

2. Embryo stage (2 to 8 weeks)

Period of rapid growth, key organs and structures develop

Question 19

The prenatal development stages

Stage three - Foetus stage

Answer 19

3. Foetus stage (9 weeks to birth)

Time of growth and development of organs

Question 20

The Germinal Stage in detail

Answer 20

Conception starts when a sperm penetrates the membrane of an ovum (egg)

When the two combine, a complete set of genetic instructions is formed, half from either gamete (sex cell)

The fertilised egg is now called a zygote - fewer than half of zygotes survive

Question 21

What is a gene?

Answer 21

A short segment of a chromosome - which are molecules of DNA

Question 22

How many chromosomes does the average person have?

Answer 22

23 pairs, one pair from the mother and one pair from the father

Question 23

Sex Determination

Which pair of chromosomes determines a persons sex? What is sex?

Answer 23

Sex is the biological category a person is places into based on their reproductive functions - male or female

The 23rd pair of chromosomes determines a persons sex

Question 24

Sex Determination

What are the shape differences between female and male chromosomes?

Answer 24

Females have two x shaped chromosomes (XX)

Males have one X and one smaller Y shaped chromosome (XY)

Question 25

Sex Determination

How does sex determination work?

Answer 25

It is the Y chromosome that leads to the development of a male, so sex is determined by which sperm X or Y fertilises the egg

Question 26

Sex Determination

How does sex determination work?

Explain prenatal sex differences…

Answer 26

It is the Y chromosome that leads to the development of a male, so sex is determined by which sperm X or Y fertilizes the egg

Sperm that carry a Y chromosome (as this is smaller) tend to be lighter and swim faster than those that carry an X, as a result 120-150 males are conceived to every 100 females

HOWEVER the ratio at birth is only 106 males to every 100 females… WHY?

Question 27

Why are boys more vulnerable prenatally??

Answer 27

Boys are more vulnerable in the womb…
- more susceptible to stress - more likely to be miscarried/ birth complications

This may be because they have only have one X chromosome. Therefore, if they have a defective gene on the X chromosome, they do not have a functioning copy to balance this out (as their other chromosome is Y).

Question 28

How do monozygotic twins develop?

Answer 28

Sometimes a growing cell cluster breaks apart early in development and results in with identical genes - the clusters develop into identical twins (they come from the same zygote)

Question 29

How do dizygotic twins develop?

Answer 29

Sometimes two different eggs are fertilized at the same time, leading to non-identical twins

Question 30

Embryonic period overview in more detail

Answer 30

2-8 weeks - core organs develop

Once the zygote has attached to the uterine wall it develops into an embryo (inner cell mass becomes embryo and the rest becomes the amniotic sac and placenta)

Amniotic sac - membrane filled with fluid for even temperature and cushioning

Placenta - allows exchange of materials from the mother to the embryo/foetus through blood via blood vessels that make up the umbilical cord

Question 31

The embryonic period marks a time of rapid development in three key structures…

What are these structures? explain…

What happens after this?

Answer 31

The inner cell mass divides into three layers:

1. Ectoderm (top layer) - becomes the nervous system, nails, teeth, inner ear, lens of the eyes and skin
2. Mesoderm (middle layer) -
   becomes the muscles, bones, circulatory system, inner layers of the skin and internal organs
3. Endoderm (bottom layer) -
   becomes the digestive system, lungs, urinary tracts and glands

After the three layers differentiate, a U-shaped groove forms down the centre of the top layer and the top of the groove fuses forming the neural tube - this becomes the brain and spinal cord

Question 32

Foetal period in more detail

Answer 32

9 weeks to birth

This period is all about growth and further development. Areas near the head develop earlier than those further away from the head

Question 33

Foetal period in more detail

Answer 33

9 weeks to birth

This period is all about growth and further development. Areas near the head develop earlier than those further away from the head.

last five months - lower parts develop more rapidly and so do the foetuses movements.

Development of sexual organs takes place early in this period. All humans (regardless of whether they are male or female) can develop either male or female genetalia (intersex etc)

It is the presence or absence of androgens (hormones that include testosterone) that cause male genitalia to develop

Question 34

Prenatal development is a function of…

Answer 34

Mainly, the zygote’s genetic code (nature).

But the environment (nurture) also plays a role.

Question 35

Environmental influences on prenatal development…

What are teratogens?

What does the effect of teratogens depend on?

Answer 35

Environmental
- agents (such as drugs), - diseases (such as German measles)
- physical conditions (such as malnutrition)
that can affect the growing embryo/foetus.

Teratogens can impair prenatal development, leading to birth defects or prenatal death.

The effect of teratogens depends on timing and the dose-response relationship (the greater the exposure the more likely the damage)

Question 36

Alcohol as a teratogen…

Overview and foetal alcohol syndrome

Answer 36

When alcohol crosses the placenta (into the foetuses bloodstream and amniotic sac) concentrations quickly equalize BUT alcohol stays in the foetuses bloodstream for longer (and in the fluid in the amniotic sac).

This can lead to heightened activity reflexes and abnormal startle reflexes.

Consuming a lot of alcohol while pregnant can lead to FOETAL ALCOHOL SYNDROME

Symptoms include:

• facial defects
• hyperactivity
• behavioural problems