Biological Methods Flashcards
What are brain scans? Give specific descriptions of PET, FMRI, and CAT scans
Also known as neuroimaging because these scans generate images about the nervous system
PET
- injected with a tracer
- sees where glucose is used up
- leads to gamma rays being emitted because of the radioactive atoms broken down
- glucose activity (also concentration of gamma rays) is linked to brain activity
- creates: colour image with ‘hot spots’
FMRI
- head placed inside a large and powerful electromagnet
- areas with high demand for oxygen are the active areas detected
- creates: (on a computer) ‘map of activation’ showing change of neural activity in brain areas
CAT
- multiple x-ray beams passed around the head at different angles
- creates: 2D pictures of brain tissue
What are strengths and weaknesses of said brain scans?
General
+can be checked by another person so making it an objective way of measuring brain structure and function therefore it is scientific
+measures brain structure and brain activity as visible and measurable results therefore increased validity
- not an everyday activity therefore lacks ecological validity
- cannot establish causality (e.g., did aggression cause change in brain structure or the other way around?)
PET
+show how the brain is functioning
+scientific
- focusing on active areas so reductionist (needs to take into account complex interconnection between the different parts)
- long-term effects of radiation
FMRI
+sensitive to changes in blood flow so high degree of accuracy
+less ethical issues (no danger from radiation, less invasive as it does not involve injection)
- may not be applicable for people with brain damage as this may affect blood flow
- can involve measuring brain ‘at rest’ but this may be difficult to get a baseline as we never stop thinking
CAT
+not painful and not invasive
+detects damage in brain which can help surgeons plan their procedures (thus reducing the time it takes for the patient to be under anaesthetic)
- doesn’t give information on how the brain is functioning
- exposure to x-rays so cannot be used frequently and may be harmful to use on pregnant women
Where are brain scans used in biological psychology?
Raine
- 41 criminals pleading for NGRI and 41 control
- Did a continuous performance task (CPT) while their brain got scanned
- used a PET scan and was injected with a tracer beforehand
- results showed differences in size of amygdala, and deficits in the corpus callosum, limbic system and prefrontal cortex
(For strengths and weaknesses for using all the methods mentioned, refer to flashcard prior these types of flashcards)
What are twin studies?
Tests done on either monozygotic or dizygotic twin to compare behaviour and concordance rates (groups that are the most similar). The test is done to see the influence of nature and nurture on human behaviour
What are strengths and weaknesses on twin studies?
+provides evidence in the nature and nurture debate
+produces quantitative empirical evidence which is an objective and scientific way of comparing data
- raised together (either link this to difficulty in untangling the influence of nature from that of nurture or link to the similar experiences of MZ twins from being treated the same explaining the high concordance rate)
- unique as they are twins so may be difficult to generalise to the wider population
Where are twin studies used in biological psychology?
Gottesman and Shields
*aim: genetic contribution to schizophrenia
*57 pairs (24 MZ and 33 DZ)
found a higher concordance rate in identical twins so there may be a genetic element to why people develop schizophrenia
What are correlational studies?
Measuring two different variables to see if there is a relation, and if there is, how strong said correlation is. May be positive, negative, or no correlation found
What are strengths and weaknesses of correlational research?
+use of quantitive data allows for objective analysis. So you can use inferential statistical tests to determine whether results are significant (Spearman’s Rho) and therefore increases internal validity
+more cost-effective (a way of investigating if there is a relationship before committing to a more expensive and detailed research)
- you cannot establish causality
- IF secondary data is used, then the researches does not know how this has been collected and if there was a high degree of control which may decrease validity
Where is correlational research used in biological psychology?
Dabbs
- aim: investigate whether testosterone is linked to criminal behaviour
- used the saliva samples of 692 male prison inmates
- found that there was a correlation between testosterone and violence and sexual related crimes, as well as disobedience in prison
What are adoption studies?
Groups of adoptees are studied and their behaviour is corelated with either their adopted families and biological families to find if there is correlation in behaviour and thus if their behaviour is the result of nature or nurture
What are the strengths and weaknesses of adoption studies?
+separating genes from the environment means it is the best method for measuring behaviour to see if it is the result of nature or nurture
+developmental trends can be looked at as the studies can be longitudinal in nature
- sample sizes tends to be limited so generalising the results may be an issue
- impossible to separate nature with nurture (e.g., spending some time biological family before adoption, time spend in foster care as a confounding variable, adoptees tend to be placed in families which closely reflect their family background, etc.)
Where are adoption studies used in biological psychology?
Heston
- aim: look at the genetic contribution to schizophrenia
- used 47 participants whose biological mother had schizophrenia and had no further contact; matched with 50 controls
- found an influence in genes but there must be other variables involved as half of the participants grew to be successful adults
