Lifespan development (cognitive, physical, social and emotional) - Chapter 12
and 13
Cognitive factors can influence social development and social factors can influence cognitive
development – both are not mutually exclusive.
Major issues and methods in developmental psychology
Examining social, biological and physical changes as we grow, whilst studying the causes of these
changes. Broad issues arising from the study of developmental psychology:
- Stability vs change: what changes as we age and what becomes stable when we reach
adulthood?
- Continuity vs discontinuity: Is development gradual and depends on the person’s own
experience or does it happen at specific ages and times?
- Nature vs nurture: to what extent is development hereditary or a product of the
environment?
- Critical vs sensitive periods: Critical periods are periods where a child must undergo a
specific development in order to proceed normally, Sensitive periods are when a child
should usually develop in a certain period, but fluctuation does not affect growth entirely;
there is some wiggle room with developing earlier or later.
Cross sectional design: comparing people of different ages at the same point in time to see of there
are difference across them regarding specific variables, such as IQ.
Cohort: people who grew up with similar historical event experiences due to being the same age.
This interferes with the abilities of those with different ages, since these periods of times have
substantially different levels of skill and developmental abilities. Cannot compare the IQ of a 60-
year-old to a 20-year-old as they are of different cohorts (different kind of education between them)
and the 60-year-old may have had some cells atrophied or they have poor reflexes.
Longitudinal studies: studying the same group or person as they age over the years. These take
forever to gather data for, and people can withdraw from the study of time.
Sequential design: combines longitudinal and cross-sectional designs, studying two different cohorts
over a few years. Very costly and time consuming. A pro of longitudinal designs is that they measure
individual differences of certain people compared to another instead of looking at entire cohorts –
shows individuality.
Micro genetic studies: same as longitudinal studies but they measure finer details due to being
carried out over shorter time spans. This allows us to observe how small-time events can influence
development and we do not have to wait for years to notice changes.
All designs have their pros, for example, studying cohorts allow us to observe the traits of people
with a similar quota (homogenous sample) to then see if their environment had more of a play in
their life than their genetics (they were born in the same generation and likely went to the same
school, so it is clear genetics is also at play in determining some features of personality).
, Prenatal development
The germinal stage is when the egg is to be fertilised by a sperm. This fertilised egg is called a zygote.
After cell division, the zygote becomes a cluster of cells that attaches to the uterus 15 days after
conception. Genetic makeup is determined when the egg is fertilised.
The mass of cells produced is called an embryo. This stage lasts until 8 weeks, where the placenta,
where there are a lot of membranes to pass nutrients through to the umbilical cord from the blood.
The umbilical cord carries these nutrients to the embryo to feed it oxygen and the nutrients. This
causes the embryonic cells to divide and become specialised, developing into organs. The embryo
beats at 8 weeks.
The foetus develops from week 9 until birth. Muscles strengthen and then the bodily systems
develop, with the baby getting to the age of viability at around 22-26 weeks. This age means that
under provisional care, if a baby is born prematurely, they can be well kept and survive. Normal
babies are born at 38 weeks. The human gestation period is 9 months.
Genetics and epigenetics
The zygote has all 46 chromosomes, with 23 pairs. Egg cells and sperm cells have 23 each. If males
have an XY pairing on the 23rd chromosome in their sperm cell, it instigates male sexual
development, due to TDF (testis determining factor), but if the sperm cell has XX on the 23 rd
chromosome, development carries on as usual, birthing a girl. At week 6-8, if XY chromosomes were
present at conception, then testes are formed to then release androgens, stimulating male organ
development.
Epigenetics are the means in which genes are expressed. The chemical environment determines
what way some genes are expressed. Every cell has the same DNA but depending on where they
produce proteins in the body, different cells carry out different tasks, from bone development to
neuronal activity in the brain.
Threats to prenatal development
Teratogens are any chemicals or agents that can cause abnormal prenatal development. These
involves drugs or smoke inhalation. The placenta tries to stop these chemicals from penetrating the
membranes and going through the cord into the foetus, but this is not always possible. Mothers
should not drink and both parents, or any nearby relative or friend, should not smoke, as intake from
second-hand smoke can cause issues. Cocaine or meth addicted mothers give birth to children who
suffer from withdraw. This causes them to be extremely cranky, teary and later, aggressive. Their
cognitive abilities and arousal control is impaired.
A naturally produces teratogen is cortisol or any stress hormone, which, from prolonged exposure,
can lead to premature birth. The most dangerous teratogen is the zika virus, which can cause
children to be born with small brains and heads.
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