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The Central Nervous System (CNS) Consists of the brain and spinal cord. Connecting to the CNS are
the nerves that control the body.
Neurones A nerve cell which sends electrical messages called nerve impulses along their length.
Neurotransmitter A chemical released at the end of a neurone to pass a message on to another
neurone, a muscle or a gland.
Synapse The space between two neurones which is crossed by chemicals called neurotransmitters.
Receptor Specialised locations on the surface of a neurone to which neurotransmitters attach
resulting in potential action.
Genes Units of information that are inherited from our parents.
Hormones A chemical which is released from a gland travels in the blood and affects the target
Brain lateralisation The differences between the left and right hemispheres of the brain.
Twin studies Psychologists look at concordance rates (the likelihood that if one twin has a certain
trait then the other twin will have the same trait) between monozygotic and dizygotic twins. Most
twins share the same environment and upbringing. They attend the same school so intelligence may
not be related to nature. So psychologists study identical twins that have been raised apart.
Adoption studies Behaviour is compared to biological parents and adoptive parents. If there is a
similarity between the behaviour of the child and their biological parent then it is a result of nature.
Evaluation of twin studies and adoption studies
Both good for studying genetic causes of behaviour, they study people who share close
genetic links but do not share the same environment.
Even twins separated at birth have shared the same environment, a womb, for 9 months.
They share a pre-natal environment.
Twins adopted and reared separately often share similar environmental experiences as
adoption agencies try to find similar background families for separated twins.
Number of twins raised apart is minimal so difficult to gain an adequate sample size. Difficult
Both studies could be sensitive to compare data to biological parents or twin brothers as
may be sensitive reasons why they were separated.
Many participants in twin and adoption studies are advertised for so a volunteer sample is
Consent is generally given.
May be biased sampling as only a certain type of person may apply.
MRI scan Structure of the brain. Patient is placed on a large scanner which passes a strong
magnetic field through their head. Electromagnetic waves are passed through the body by the
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PET scan Functioning of the brain. A radioactive chemical is injected into the blood of a person,
releasing radioactivity which can be picked up on the scan. The more active the brain, the more
radioactivity will be picked up by the scan. Dark areas show more activity.
Evaluation of animal studies
Animals are easier to monitor than humans.
Large samples can be bred in a short period, so the effect of stuff can be studied over
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Male speech and comprehension is controlled by the left hemisphere,
whilst females tend to be across both hemispheres.
Evaluation of the biological explanation to gender development
In the case of David Reimer, the role of genetics overcame the role of the environment in the
formation of gender.
Koopman et al attached the SRY gene to female embryos and they turned into males.
Using animals for studying biological explanations to gender is useful as they breed quickly.…read more