biological psychology all evaluation

• Owens


  Used post mortem analysis to show that Sz patients have an excess of dopamine receptors in the cerebral cortex and so are more sensitive to the action of dopamine than non-sufferers
• Allen and Stevens


  Found synaptic transmission to be very unreliable as less than half the neurotransmitters that arrive at the presynaptic neuron arrive to the postsynaptic neuron
• Jovanovic


  Used PET scans to look at the serotonin system of women (premenstrual dysphoric disorder) compared to controls and found that those with PMDD showed a difference in synaptic transmission
• Applications of the explanation as it explains changes in moods and disorders such as Sz are due to disruptions at the synapse
• Evidence from animal studies, issues with evolutionary discontinuity
• Brain scans have also been used which is a valid and scientifically credible method
• Brain scans can be used to look at neurotransmitter levels in both drug abusing and non-drug abusing individuals and then quantify the differences
• Ethical issues with human participants as you can't give someone drugs and so animals are often used instead which lacks generalisability
• Lab based research used to determine whether drugs have a particular effect on neurotransmitters, can compare people with a history of drug exposure and those who don't or may use animals who are exposed to drugs under lab conditions, this has high validity as high control over extraneous variables
• Reductionist approach as it doesn't say why we take drugs in the first place and only takes into account biological factors
• Olds and Milner


  Placed electrodes in different areas of rats brains and placed in skinner's box, found rats would self stimulate when pressing the lever especially when linked to the VTA
• Brain scans still can't get to the level of synaptic transmission so it is hard to study the mode of synaptic transmission and effect of drugs on this at the synapse
• Virkunen

  Compared levels of serotonin breakdown in the cerebrospinal fluid of violent impulsive and non-impulsive offenders and found that levels were lower for impulsive offenders
• Gorkal et al


  Used fMRI scans to study activity between PFC and amygdala, ppts who had drunk alcohol showed less brain activity as it interferes with the brain's ability to pass serotonin
• Ferrari et al


  Studied the link between NT's and aggression in rats, introduced an intruder rat 10 days in a row and then none on the 11th day but recorded levels of NT's and found that there were increased levels of dopamine and lower serotonin as they were anticipating a fight
• Lavine


  Found an increase in dopamine levels through the use of amphetamines was associated with an increase in aggressive behaviours
• Brain scans allow an in depth study of certain areas of the brain and link them to function, can identify any abnormalities for those with brain disorders
• Brain scans may not be suitable for everyone e.g. those with cardiac pacemakers cant have an fMRI scan due to the strong electromagnets used which lowers generalisability
• Daly and Wilson


  Reviewed murders and found that the motive behind most conflict was status and the victims were likely to be men of low status and without a mate
• Reductionist explanation as it ignored the role of environmental factors e.g. the importance of role models
• Hill and Hurtado


  Found that among the Ache of Paraguay, children were 5 times more likely to die if the mother dies and 100% likely if this happened before the age of 1
• Griskevicius


  Has found sex differences in aggression for both direct and physical aggression (more seen in males) and for indirect and verbal aggression (seen in females more)
• Doesn't account for cultural differences, e.g. among the Yanomamo male violence is required to attain status whereas in the Kung San aggression only leads to reputational damage
• Unfalsifiable explanation as the behaviours were seen thousands of years ago so cannot be proven or disproven
• Dabbs and Hargrove

  Measured testosterone in 87 female inmates and found the degree of criminal violence used by women was positively correlated with testosterone level, testosterone also correlated with womens aggression dominance within the prison
• Results are purely correlational and doesn't mean that testosterone is the cause of aggression as there may be a third variable involved
• Hormones can be measured using blood tests, saliva samples and using spinal taps of cerebrospinal fluid which is objective and measurable
• Mazur and Booth found that testosterone levels varied across lifespan according to environmental status e.g. being married decreased testosterone levels, therefore without a baseline to compare to it is hard to create clear cause and effect
• Barzman


  Found that the amount of cortisol in the saliva correlated with the number of aggressive acts recorded by nurses and the amount of aggression on the first aggressive incident
• If aggression is chemically controlled it could lead to manufacturing a drug that influences the hormonal mechanism and reduces aggressive behaviours e.g. MPA reduces sexual aggression
• Case studies


  • High in validity as lots of data, both quantitative and qualitative, can be gathered and triangulated
  • Lack of control variables which may decrease the validity of the findings
• Can be used to explain different types of aggression with 'hot blooded' aggression being explained by the satisfaction of the id whereas 'cold blooded' aggression which is more cold and calculating can be explained by the egos attempt to control the id impulse
• Unfalsifiable explanation such as the ego and the id which cannot be seen in quantifiable units
• Can lead to useful applications such as psychoanalysis which is a better treatment than previous more unethical treatments such as electroconvulsive therapy and it has been shown to be very successful in women
• May be issues with researcher bias as Freud's research came after his theory so he may have viewed the results in light of supporting his theory and ignored research that didn't support it
• Bredgen


  Large sample used so unusual children with very high or low levels of aggression would be averaged out by the size of the data, increasing validity
• As a natural experiment it can't show cause and effect for example, the twins might influence one another's behaviour and lead them astray
• The study provides a holistic view of aggression as it looks at both environmental and genetic factors
• The study requires the children to look at pictures of their classmates and judge them which may cause issues with friendships especially if the children shared who they picked afterwards, could lead to revenge, goes against the social responsibility of protection from harm
• The allocation of zygoticity (MZ and DZ categories) was largely based on appearance and so not a valid measurement of zygoticity