Biological SAQ Flashcards
Maguire et al(2000)(London Taxi driver)
localisation+neuroplasticity for spatial memory
Aim: to investigate the growth of hippocampus in London taxi drivers in relation to their navigation experience
Procedures:
-Quasi-experiment and correlational studies
• The participants were 16 right-handed male licensed taxi drivers and 50 healthy right-handed male subjects who did not drive a taxi.
• Brain scans of control subjects were obtained by MRI .
• Compare MRI scans of the brains of London cabbies and non-cabbies
-Researcher correlated the number of years of taxi driving experience with the results of the MRI scans.
Result:
• An increased brain matter volume in the posterior hippocampus of taxi drivers compared to the control group
• the control group has greater volumes of grey matter in the anterior hippocampus
• The increasing volume of the hippocampus is the same, the redistribution of grey matter from the anterior to posterior hippocampus are different.
• The “shift” of brain matter is related to taxi drivers’ experiences as a result of neuroplasticity
• posterior-learnt spatial information
anterior-learning new spatial information
-A correlation was observed between the number of years of taxi driving experience and grey matter volume in the hippocampus: the longer they drove a taxi, the larger the volume of their posterior hippocampus.
Evaluation:
• The result lacks certainty—just correlation, no cause-and-effect relationship
• Many variables are controlled: the control group, the mean age and gender
• Ethics: informed consent+ use of data. The participants have informed consent.
H.M case study
A: to investigate the removal of hippocampus in relation to localization of the brain
P: HM suffered from epilepsy.
• Went through lesioning to remove temporal lobe.
• Surgeon accidentally removed parts of the Hippocampus (responsible for LTM retrieval).
• The researcher did a MRI scan of H.M’s brain as they found that parts of the temporal lobe, including hippocampus were missing.
R:
• After the surgery, his personality remained unchanged but he could not form new memories. He suffered from amnesia.
• H.M could retain memories of what had happened before the surgery.
• HM was also capable of retaining new information for a while if he rehearsed it,but he would forget it afterwards.
• The hippocampus plays an important role to transfer short-term memory to long-term memory.
E:
• High ecological validity: study of a real life case.
• Longitudinal research: contribute to the new understanding of memory processing
• Results could not be generalized because cases are individual.
• Ethics: Patient’s name was kept confidential until he died.
Animal Study: Rogers & Kesner
Acetylencoline(ACH)
Role: consodilation of memory in hippocampus,spatial memory
A: to determine the role of acetylcholine in the formation of spatial memory
P:
• 30 rats acclimate(be calmed down) to a maze by placing food in one of the corners, research begins when rats are comfortable with the maze
• The rats were randomly allocated to one of two conditions(they were injected with scoplamine blocks the ACH receptor sites and inhibits response or a saline solution placebo injection /make sure not responsible for a change in memory 10 minutes before running the maze)
• Encoding memory was assessed by the average number of errors made on the first five races
R:The sc group took longer and made more mistakes in the learning of the maze,no impact on the retrieval of memories had already been created
C:ACH may play an important role in the consolidation of spatial memories
E:
Strengths:
• a rigorously controlled experiment under a placebo condition-avoid the effect of confounding variables
• Strong applications–the development of treatment from dementia or Alzheimer’s disease
• randomly selected–animals are similar to humans
• Biologists believe that animals can serve as models for human physiology and behavior
Limitations:
• A reductionist approach to understand memory–didn’t explain the complexity of types and process of memory consolidation
Newcomer et al(1999)
Aim:
To investigate the effects of high levels of the stress hormone cortisol on verbal declarative memory.
Cortisol is a steroid hormone that is produced by the adrenal glands. Cortisol can help control blood sugar levels, regulate metabolism, help reduce inflammation, and assist with memory formulation.
Procedures:
• Participants–selected sample of 51 normal and healthy people aged 18-30
• Condition 1 – high level of cortisol: The participants were given a tablet containing 160 mg of cortisol on each day of the four-day experiment. This dose of cortisol produces blood levels similar to those seen in people experiencing a major stress event.
• Condition 2 – low level of cortisol: The participants were given a tablet containing 40 mg of cortisol per day. This dose is similar to the amount of cortisol circulating in the bloodstream of people undergoing minor surgical procedures such as having stitches removed.
• Condition 3 – placebo group: The participants in this condition were given placebo tablets .This was done in order to have a control group.
• All participants were asked to listen to and recall parts of a prose paragraph. This tested their verbal declarative memory.
Results:
• In the placebo group, paragraph recall performance improved over the course of the four days, most likely due to a practice effect. In contrast, the cortisol treated participants did not show an overall improvement.
• The performance of participants in the high cortisol condition returned to normal after they stopped taking the hormone tablet.
• The results indicated that high cortisol levels impaired performance in the memory task since the participants who received the highest level of cortisol also showed the worst performance in verbal declarative memory.
• There is a clear link between levels of cortisol and remembering.
• Cortisol interferes with the transfer of short-term memory to long-term memory that takes place in the hippocampus because there are several cortisol receptor sites on the hippocampus
Evaluation:
• The researchers could establish a clear cause-and-effect relationship between the IV and the DV
• There was a clear relationship between the amount of cortisol ingested and the performance on the memory test
• Ethical considerations: the participants have signed the consent form and there was no permanent damage
Cutler et al(1998)
Aim: to investigate whether synthesized male pheromones increase sociosexual behavior of men
Procedures:
• 38 healthy, heterosexual male participants age 25-42 were recruited
• a double-blind experiment was carried out as the participants were randomly divided into two groups
• the participants has to use an aftershave lotion at lease three times a week throughout two weeks
• then the next six weeks, one group were using the aftershave lotion with a synthesized pheromone, and another group were using the lotion with ethanol
• they were asked to record their frequencies of sexual behaviors through the study period
Result:
• there was a significant increase of sexual behaviors in the pheromone group compared with the placebo group
• 47% of men in the pheromone condition reported an increase in the frequency of sexual intercourse compared to 9.5% in the placebo group
• applying the synthetic pheromone resulted in an increase of sociosexual behaviors of men
Caspi et al (2003)
Serotonin is a neurotransmitter which regulates anxiety, happiness, and mood. Low levels of the chemical have been associated with depression, and increased serotonin levels brought on by medication are thought to decrease emotional arousal.
A: to determine whether there is evidence for a gene-environment interaction for a mutation of the serotonin transporter gene–5-HTT
M: Correlational study was used to hypothesize whether or not genes can moderate human behaviour.
P:
• 5-HTT gene influences level of serotonin (control mood)
• Compare participants with a normal 5-HTT gene and a mutation of the 5-HTT gene with shorter alleles
R:
• Participants who carried a mutation of 5-HTT gene have 80% to become depressed than normal 5-HTT gene after stressful events
• Adult depression due to childhood mal-treatment oly discovered in those with short alleles
• The 5-HTT gene indicate a vulnerability to depression after stress which suggests that gene could moderate individual responses to environmental factors
E:
• Correlational (no cause-and-effect relationship)
• It’s an assumption
• Environmental factors should also be considered
• Holistic approach(not reductionist), environmental factors could also be considered
Sullivan et al
Aim To investigate the genetic influence on major depression
Method Meta-analysis of twin studies, including over 21,000 twins
Results • MZ twins more than twice as likely to develop major depression if their co-twin had the disorder compared to DZ twins
• Genetic influence in developing major depression was between 31% and 42%
• Non-shared environmental factors also important
Conclusions • Major depression is a familial disorder with a strong genetic component
• Complex disorder due to the interaction of genetic and environmental influences
• Depression is the result of several genes that act together to produce a vulnerability to depression when other risk factors are present
Twin Studies
• To study the possible correlation of genetic inheritance and behaviour
• MZ(monozygotic)identical,one egg splits into two,100% similarities
• DZ(dizygotic)fraternal,two eggs,50% similarities
• Psychologists use these degrees of genetic relationship as a basis for their hypotheses about the contribution of genetic and environmental factors to behaviours such as psychatric disorders or addictive behaviour
• It’s based on a systematic analysis between MZ and DZ,MZ twins have higher concordance rate
• The concordance rate: the probability that the same trait will be present in both members of a pair of twins
• If CR is high for both MZ and DZ,environmental factors play an important role
If CR for MZ is higher,the genetic component to the behaviour
Warheken et al (2007) (animal and human study)
A: to investigate whether humans have a genetic predisposition for altruistic behaviour
M: independent samples design
P:
• Approx. 20 chimps born in the wild, approx. 20 human infants
• Chimp group: condition 1–researcher reach for a stick that was too high for him to get.
condition 2– researcher started at a stick which was too high for him to get
The chimps had to climb up in order to help the researcher.
• Human infants group: condition 1–researcher dropped a pen and reached for it
condition 2– researcher dropped a pen but did not reach for it.
R:
• Both chimps and children helped the researcher more than 50% of the time.
• Chimps took longer than children to understand altruistic behaviour, but still helped at the same frequency
• Humans and chimps are both hardwired for helping behaviour– altruistic behaviour has an evolutionary origin.
Evaluation:
• They have already participated in previous studies of prosocial behaviour, they might be conditioned to helping behaviour.
• Human behaviours might be influenced by culture (Enculturation–children would have been exposed to helping behaviour at home)
• Reductionist to explain the complexity of human behaviour
Lack scientific (empirical) evidence to explain that genes are responsible for helping behaviour.
Madsen et al – cross-cultural study of Kin-selection theory
Experimental design Experiment, Repeated measures design
Aim To test the kin selection hypothesis in two contrasting cultures
Essential understanding Participants are more willing to endure pain when it benefits closer relatives. This pattern repeats cross-culturally.
Sample South African and UK students
Procedure • Participants asked to perform a ‘wall squat’ – physical exercise that becomes increasingly painful
• Each participant previously supplied list of biological relatives, not including those who shared a home with the participant
• Prior to each trial, participants told that one relative randomly selected from the list would receive payment or goods according to the length of time the participant remained ‘seated’ against wall
Results • Trend– the amount of time spent in the painful position increased with the co-efficient of relatedness
• Both groups of participants spent longer in position when money was given to more closely related family members
• South African participants did not seem to distinguish between cousins and biologically closer relatives such as siblings, aunts and nephews
Conclusion Kin selection is a powerful motivator to perform altruistic behaviours
Provide experimental evidence that kinship plays a role in moderating altruistic behaviour. Kinship has an influence over and above other possible factors.
Strengths Cross cultural study – highly generalisable
Limitations Variable of relatedness cannot be manipulated by experimenters – prevents clear isolation of cause and effect
