Lecture 1: Prenatal Development Flashcards
What is developmental psychology?
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
Outline some of the WAYS development is studied
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
Outline some DOMAINS in which development is studied
Physical development - body, brain, senses, motor skills e.g. reaching and crawling
Cognitive development - learning, memory, language, reasoning
Psychosocial - personality, emotions, social relationships
Outline some fundamental issues in developmental psychology…
(4 issues)
- Individual differences -
People develop along different trajectories - Sources of development -
nature or nurture?? - Continuity vs discontinuity -
series of small and continuous changes? abrupt transformations? discontinuous stages? - Plasticity -
open to change? when do changes have the greatest impact?
Name 3 reasons to study developmental psychology…
- Choosing social policy
- Raising children
- Understanding human nature
Name the two methods for understanding change…
Explain them…
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
Name the 3 methods for understanding change…
Explain them…
(Types of studies)
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
The three methods for understanding change (study types)
compare them…
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)
+/- of cross sectional studies
Strength - not time consuming
Weakness - cant see how individual children change
+/- of longitudinal studies
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
+/- of microgenetic studies
Strength - precise descriptions of development
Weakness - intensive, small samples, practice effects
How can experiments be used in developmental psychology?
As well as looking at change, experiments can be used to test the effect of variables on childrens’ skills or abilities
What is preformationism?
The popular belief (until the 1600s) that miniature people lived in sperm and started to grow upon fertilisation of the egg
What is epigenesis?
The term used to describe what we know
What is epigenesis?
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
What is prenatal development?
Development occurring from zygote to birth
The prenatal development stages
Stage one - Germination Stage
- 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
The prenatal development stages
Stage two - Embryo Stage
- Embryo stage (2 to 8 weeks)
Period of rapid growth, key organs and structures develop
The prenatal development stages
Stage three - Foetus stage
- Foetus stage (9 weeks to birth)
Time of growth and development of organs
The Germinal Stage in detail
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
What is a gene?
A short segment of a chromosome - which are molecules of DNA
How many chromosomes does the average person have?
23 pairs, one pair from the mother and one pair from the father
Sex Determination
Which pair of chromosomes determines a persons sex? What is sex?
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
Sex Determination
What are the shape differences between female and male chromosomes?
Females have two x shaped chromosomes (XX)
Males have one X and one smaller Y shaped chromosome (XY)
Sex Determination
How does sex determination work?
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
Sex Determination
How does sex determination work?
Explain prenatal sex differences…
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?
Why are boys more vulnerable prenatally??
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).
How do monozygotic twins develop?
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)
How do dizygotic twins develop?
Sometimes two different eggs are fertilized at the same time, leading to non-identical twins
Embryonic period overview in more detail
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
The embryonic period marks a time of rapid development in three key structures…
What are these structures? explain…
What happens after this?
The inner cell mass divides into three layers:
- Ectoderm (top layer) - becomes the nervous system, nails, teeth, inner ear, lens of the eyes and skin
- Mesoderm (middle layer) -
becomes the muscles, bones, circulatory system, inner layers of the skin and internal organs - 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
Foetal period in more detail
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
Foetal period in more detail
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
Prenatal development is a function of…
Mainly, the zygote’s genetic code (nature).
But the environment (nurture) also plays a role.
Environmental influences on prenatal development…
What are teratogens?
What does the effect of teratogens depend on?
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)
Alcohol as a teratogen…
Overview and foetal alcohol syndrome
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
