- Created by: Charlotte Donker
- Created on: 13-10-14 02:59
Hetherington and Ranson (1942)
Aim: To investigate the relation of various hypothalamic lesions to adiposity
P: They conducted a study on rats in a lab. The three independent variables are the three different types of rats, by lesioning the rats brains, it separated them into rats that had lesioning to the lateral hypothalamus, ventromedial hypothalamus, and rats who had no lesions, which acted as a controlled group. The rats were then observed for several weeks after the procedure, while being kept in a cage with food and water. Their food and water intakes were monitored.
Findings: They found that lesions in the lateral hypothalamus caused the rats to stop eating whereas the lesions in the ventromedial hypothalamus caused the animals to overeat, therefore they were obese.
Conclusion: The animals with smaller hypothalamic lesions do not attain as high level of adiposity as those with the larger lesions, nor is the onset of the obesity quite so rapid. It can be due to the failure of the smaller lesions, the lesions weren’t able to destroy the cells and fibers which is necessary for the normal process of fat metabolism.
Maguire et al
Aim: To investigate the navigational experience and the role played by the hippocampus in humans, and whether the healthy human brain can undergo 'plastic' (structural) changes in response to extensive navigational experience.
Procedure: It was a natural experiment with an independent measures design. The independent variable was the amount of navigational experience and the dependent variable was the volume of the hippocampus. 16 healthy male taxi drivers and 50 healthy male non-taxi drivers (Control group) received an MRI scan. They were analysed by VBM, which produced templates of scans and compared the taxi drivers' brains with the control group to see if there were any structural differences in the brain, and Pixel counting, in which a experienced observer compared the volume of the anterior, body, and posterior cross-sections of the taxi drivers' hippocampus' with those of a precisely matched control group.
Findings: On the VBM, there were no significant differences elsewhere in the brain between the two groups, however the taxi drivers had significantly increase grey matter volume in the right and left posterior hippocampus' compared to the controls. When pixel counting,taxi drivers had a larger volume in the posterior hippocampus' compared to the controls, the control group however had a larger volume in the anterior hippocampus'.
Fisher et al
Aim: To investigate the neutral mechanisms associated with the attraction system.
Procedure: 10 women and 7 men aged 18-26, who were in a recent relationship of an average of 7.5 months, first filled out a questionnaire to investigate how they felt about their relationship. Then they were placed in the fMRI scanner. They first saw a photograph f their beloved, then performed a maths problem, before looking at a photograph of a neural acquaintance. This was repeated six times.
Findings: The findings showed that there was increased activity in the dopamine rich brain areas associated with reward, motivation, and goal orientation when participants looked at their lover. The results indicate the possibility of brain circuits dedicated to attraction.
Conclusion: The same brain circuits have been associated with addiction, which could support the hypothesis that love is an addiction. Fisher argues that "romantic love" is universal and based on neurobiological factors.
Link back: Technology is used to investigate the relationship between Dopamine, a neurotransmitter, and love and in turn, addiction.
Rosenzweig and Bennet (1972)
Aim: To investigate the effects of a deprived or enriched environment on neuroplasticity, in particular, the development of neurons in the cerebral cortex
Procedure: The researchers placed rats into one of two environments to measure the effect of either enrichment or deprivation on the development of neurons in the cerebral cortex. The enriched, stimulating environment was characterized by interesting toys to play with.The deprived environment was characterized by no toys. The rats spent 30 to 60 days in their respective environment and then they were sacrificed.
Findings: Post-mortem studies of their brains showed that those that had been in the stimulating environment had an increased thickness in the cortex. The frontal lobe, which is associated with thinking, planning, and decision making, was heavier in the rats that had been in the stimulating environment. Similar research studies have constantly demonstrated that cortical thickness increases even further if the rats are placed with other rats.
Conclusions: The combination of having company and many interesting toys created the best conditions for developing cerebral thickness.
Baumgartner et al (2008)
Aim: To investigate the role of oxytocin after breaches of trust in a trust game.
Procedure: The participants played a trust game used by economists and neuroscientists to study social interaction. The “investor” (player 1) receives a sum of money and must decide whether to keep it or share it with a “trustee” (player 2). If the sum is shared the sum is tripled. Then player 2 must decide if this sum should be shared (trust) or kept (violation of trust). fMRI scans were carried out on 49 participants. They received either oxytocin or placebo via a nasal spray. Participants played against different trustees in the trust game and against a computer in a risk game. In 50% of the games their trust was broken. They received feedback on this from the experimenters during the games.
Findings: Participants in the placebo group were likely to show less trust after feedback on betrayal. They invested less. Participants in the oxytocin group continued to invest at similar rates after receiving feedback on a breach of trust. The fMRI scans showed decreases in responses in the amygdala and the caudate nucleus. The amygdala is involved in emotional processing and has many oxytocin receptors. The caudate nucleus is associated with learning and memory and plays a role in reward-related responses and learning to trust.
Bouchard et al (1990)
Aim: To investigate the concordance rate of the IQ's of monozygotic twins raised apart (MZA) and monozygotic twins raise together (MZT).
Procedure: This was a longitudinal study conducted since 1979.
HM fell off his bicycle when he was 7 years old, injuring his head. He began to have epileptic seizures when he was 10. By the age of 27 the epileptic attacks prevented him from living a normal life. Scoville performed an experimental surgery on H.M.’s brain to stop the seizures. Specifically he removed parts of HM's temporal lobes (part of his hippocampus along with it).The seizures stopped but H.M. suffered from amnesia for the rest of his life. The case study of H.M. provides information on how particular brain areas and networks are involved in memory processing. This helped scientists to formulate new theories about memory functioning.
H.M. could no longer store new memories (anterograde amnesia). Most of his memories from before the operation remained intact (partial retrograde amnesia). He could not transfer new semantic and episodic memories (explicit memories) into LTM. He was able to carry on normal conversations (i.e. had some capacity for working memory) but he would forget what the conversation was about immediately. The hippocampus play a critical role in converting memories of experiences from STM to LTM (the permanent store). H.M. was able to retain some memories for events that happened long before his surgery. This indicates that the medial temporal region with the hippocampus is not the site of permanent storage in itself. It rather seems to play a role in how memories are organized and then stored elsewhere in the brain. The fact that H.M. and other people with amnesia have deficits in some types of memories but not in others is taken as evidence that the brain has multiple memory systems that are supported by distinct brain regions.
Caspi et al (2003)
Aim: To investigate the role of the 5-HTT gene in depression after experiences of stressful events
Procedure: The researchers compared participants with a normal 5-HTT gene and a mutation of the 5-HTT gene with shorter alleles. Both types are quite frequenct in humans but the long allele is slightly more frequent (57%).
Findings: Researchers found that participants who carried a mutation of the 5-HTT gene and who had experinced many stressful events were more likely to become depressed after stressful events than those participatns who carried the normal 5-HTT gene. The 5-HTT gene could indicate a vulnerability to depression after stress and the researchers speculated whether the gene could moderate individual responses to environmental factors.
Brown and Kulik (1977)
Aim: To investigate whether shocking events are recalled more vividly and accurately than other events.
Procedure: Questionnaires asked 80 participants to recall circumstances where they had learned of shocking events.
Findings: Participants had vivid memories of where they were, what they did and what they felt when they first heard about a shocking public event such as the assassination of JFK. The participants also said they had flashbulb memories of shocking personal events such as the sudden death of a relative. The results indicated that FM is more likely for unexpected and personally relevant events. The researchers suggested ‘the photographic model of flashbulb memory’. Brown and Kulik suggest that FM is caused by physiological emotional arousal (e.g. activity in the amygdala)
Conclusion: Shocking events were likely to be vivid flashbulb memories, but more likely to be flashbulb memories if the event was unexpected.
Aim: To investigate how information changes with each reproduction and to find out why the information changes.
Procedure: The tests used a Native American folktale called 'The war of the ghosts' which came from a different culture from the participants. In the serial reproduction task, the first participant read the story to themselves twice. Then waited 15-30 minutes before telling the story to the second participant. Each participant in a group of 10 repeated their story to the next person. This was done with several chains of participants. In the repeated reproduction task, each participant was tested separately. They read the story to themselves twice, at their normal reading speed. After 15 minutes, the participant gave their first reproduction of the story. They could not look back at the original story. Later reproductions were done at different intervals for different participants (20 hours, 8 days, 6 months, 10 years).
Findings: Very few participants recalled the story accurately. Bartlett analysed the changes in the story and found patterns in the errors. Once a story had a particular outline it sticks, eg the order of events. Information such as names and numbers were lost. If remembered, they became stereotyped. Over a very long time they were remembered if they match the participant's interests or expectations. Events were made less complex and details were left out or are made more familiar. Inaccurate details were put in, e.g. to the building of a fire, one participant added 'probably to cook his breakfast' Serial reproductions showed the same changes as the repeated reproductions. They also showed how one individual's interpretation affected all the others in the chain.
Loftus and Palmer (1974)
Aim: To test their hypothesis that the language used in eyewitness testimony can alter memory.
Procedure: Participants were shown slides of a car accident involving a number of cars and asked to describe what had happened as if they were eyewitnesses. They were then asked specific questions, including the question “About how fast were the cars going when they (hit/smashed/collided/bumped/contacted ) each other?” A week after the participants saw the slides they were asked “Did you see any broken glass?” There was no broken glass shown in the slides.
Findings: The estimated speed was affected by the verb used. The verb implied information about the speed, which systematically affected the participants’ memory of the accident. Participants who were asked the “smashed” question thought the cars were going faster than those who were asked the “hit” question. When people were asked a week after viewing the film whether they saw any broken glass at the scene, people in the smashed group were more likely to say yes. Therefore, a leading question that encouraged them to remember the vehicles going faster also encouraged them to remember that they saw non-existent broken glass.
Conclusions: This research suggests that memory is easily distorted by questioning technique and information acquired after the event can merge with original memory causing inaccurate recall or reconstructive memory.
Aim: To find out where the brain stores the emotional memory, which pairs the tone and shock
Procedure: They began by making small lesions in different parts of the rats’ brains to see if they could derail the conditioning response. They also examined the electrical activity from a single neuron.
Findings: A lesion to the amygdala wiped out fear conditioning in the rats. To examine the signals coming into the amygdala from the thalamus and the cortex, LeDoux and his colleagues recorded electrical activity from single neurons. In general terms, they found that signals coming from the thalamus are fast and crude, reaching the amygdala before signals from the cortex, but providing only general information about the incoming stimulus. In contrast, the signals from the cortex are slow and refined, providing detailed information about the stimulus.
Speisman et al (1964)
Aim: To investigate the extent to which manipulation of cognitive appraisal could influence emotional experience.
Procedure: In this laboratory experiment, the participants saw anxiety-evoking films, such as one with an aboriginal initiation ceremony where adolescent boys were subjected to unpleasant genital cutting.These films were shown with three different soundtracks that were intended to manipulate emotional reactions. The trauma condition group has a soundtrack with emphasis on the mutilation and pain; theintellectualization condition group has a soundtrack that gave an anthropological interpretation of the initiation ceremony; the denial condition group showed the adolescents as being willing and happy in the ceremony.
During each viewing of the film various objective physiological measures were taken, such as heart rate and galvanic skin response.
Results: The participants in the trauma condition group showed higher physiological measures of stress than the participants in the other two conditions. The results support the appraisal theory in that the manipulation of the participants' cognitive appraisal had significant impacts on the physiological stress reactions. The participants in the trauma condition reacted much more emotionally.
Aim: To investigate the existence of Flashbulb Memory.
Procedure: 24 witnesses of the 9/11 incident were found from different location of Manhattan as subjects. Subjects were placed in an fMRI machine. Subjects were asked to recall the event of 9/11. Subjects were also asked to recall their summer holiday (for control purpose).
Findings: People closer to where the event happened (where the World Trade Center was) had a more in-depth recall of the event. When compared to subject's summer holiday, the level of detail given for 9/11 incident was higher. Parahippocampal Gyrus (Para-hippo-campal Gy-rus - responsible for LTM retrieval) was relatively inactive when recalling memories from 9/11 when compared to recalling events from summer holiday. Amygdala (responsible for processing memory of emotional reaction) was relatively more active when recalling memories from 9/11.
Conclusion: Different part of the brain was used for different Flashbulb Memory retrieval and general LTM retrieval. Supports Flashbulb Memory as a different type of memory than LTM. In collectivist cultures, the subjects tend to suppress emotion, and therefore the memories are encoded at a shallow level. In individualist cultures, the subjects encouraged to express emotion, and therefore the memories are encoded at a deeper level (Levels of processing theory - Craik & Lockhart)
Aim: To see if children would imitate the aggresion of an adult model and whether they would imitate same-sex more than opposite sex models.
Procedure: The participants were 36 girls and 36 boys from the Stanford University Nursery School (mean age 4.4) who were divided into three groups matched on levels of aggressiveness before the experiment. One group saw the adult model behave aggressively towards a Bobo doll, one group saw the model assemble toys and the last group served as a control group. The children were further divided into groups were they either a same-sex model or an opposite sex model. The model either played with the toys or behaved aggressively towards the Bobo doll. The children were brought into a room with toys and a bobo doll where they were observed through a one-way mirror.
Findings: The children who had seen the aggressive model were significantly more aggressive, both physically and verbally towards the Bobo doll. They imitated the aggressive behaviour the model showed as well as other forms. Children were also more likely to imitate same-sex models. Boys were more likely to be aggressive compared to the girls.
Charlton et al 2001
Aim: To investigate whether children in St. Helena would exhibit to more aggresive behaviour after the introduction of television to the island in 1995.
Procedure: The study was a netural experiment. Children (aged three to eight years) were observed before and after the introduction of television through children set up in the playgrounds of two primary schools on the island. The level of aggression in television matched what children in the UK were exposed to. The researchers also conducted interviews with teachers, parents, and some of the older children.
Findings: There was no increase in aggressive or antisocial behaviour. This was also the case after five years. The data showed that children did not change their behaviour after television arrived although they saw the same amount of violent televsision of British children.
Critisisms: The parents and teachers said that antisocial beahviour was not accepted on the island and there was a high degree of social control in the community. It shows that people may learn aggressive behaviour but they may not exhibit it for several reasons. Social and cultural factors also play a role in what behaviours are acceptable, so even though the children had no doubt learned aggresive beaviour, they did not show it.
Bond and Smith (1966)
Aim: To explore conformity through a meta analysis of Asch's studies in relation to individualism-collectivism in different cultures.
Procedure: Meta-analysis of 133 studies from 17 different countries on the Asch paradigm.
Results: They found higher conformity levels in collectivistic cultures than in individualistic cultures. The level of conformity (i.e. percentage of incorrect answers) ranged from 15% in an experiment with Belgian students (Doms 1983) to 58% among Indian teachers in Fiji (Chandra 1973). They also found that generally the conformity was higher when the majority group was large
Aim: The extent to which social pressure from a majority group could affect a person to conform.
Procedure: Asch used a lab experiment to study conformity, whereby 50 male students from Swarthmore College in the USA participated in a ‘vision test’.Using a line judgment task, Asch put a naive participant in a room with seven confederates.The confederates had agreed in advance what their responses would be when presented with the line task. The real participant did not know this. Each person in the room had to state aloud which comparison line (A, B or C) was most like the target line. The real participant sat at the end of the row and gave his or her answer last. Asch was interested to see if the real participant would conform to the majority view. Asch's experiment also had a control condition where there were no confederates, only a "real participant".
Findings: Asch measured the number of times each participant conformed to the majority view. On average, about one third (32%) of the participants who were placed in this situation went along and conformed with the clearly incorrect majority on the critical trials. Over the 12 critical trials about 75% of participants conformed at least once and 25% of participant never conformed. In the control group, with no pressure to conform to confederates, less than 1% of participants gave the wrong answer
Conclusion: Apparently, people conform for two main reasons: because they want to fit in with the group (normative influence) and because they believe the group is better informed than they are (informational influence).
Ross (1977) FAE
Aim: To investigate whether knowledge of allocated social roles in a quiz show would affect participants' judgements of people's expertise.
Procedure: Eighteen pairs of students from an introductory class at Stanford University participated in a simulated quiz game where they were randomly assigned to the roles of either questioner or contestant. Twenty-four observers watched the quiz. The questioners were asked to compose 10 questions based on their own knowledge and the contestants were asked to answer those questions. The questioner was instructed to ask each question and then wait around 30 seconds for a response. If the contestants did not answer the question correctly, the questioner gave the correct answer. After the quiz, all of the partcipants and the observers were asked to rate "general knowledge" of the contestants and the questioners.
Findings: The contestants consistently rated the general knowledge of the questioners as superior. The observers did the same. The questioners did not rate themselves as being superior to that of the contestants.
Conclusion: This is a clear demonstation of FAE. The contestants and the observers attributed the questioners' ability to answer the question to dispositional factors and failed to take into consideration the situational factors that gave the questioners an advantage.
Macolm Gladwell Korean Air
Malcolm Gladwell created a case study in reference to the cultural dimension of power distance on communication. He examined several plane crashes in which culture may have been a factor that caused the plane to crash. Fischer and Orasanu 1999's Cultural Diversity and Crew Communication study tried to identify 6 different communication strategies: commands, crew obligation statements, crew suggestions, queries, preferences and hints. In Outliers, a book Gladwell published his results in, these categories are described as degrees of mitigated speech. Mitigated speech is any attempt to sugarcoat the meaning of what is being said. Gladwell relates this study to Hofstede's cultural dimension of power distance. Power distance explores the degree to which the less powerful members of a society accept and expect that power is distributed unequally. High power distance countries include Korea, Russia and Slovakia, which means that there is a large degree of distance between hierarchical positions. Low power distance countries include United States and Finland. He studied Korean Air Flight 801, a plane crash in which power distance may have been a contributing factor in the crash. In the transcript of the crash, it is evident that the high power distance of Korea had a negative effect on the communication within the cockpit. Because of the high power distance in Korea, the first officer felt it was only appropriate to hint on problems. The first officer may have seen it as unreasonable to give a personal opinion to a higher power. This made the first pilot use mitigated speech, such as "Let's make a missed approach" as well as deference in communication such as "Today weather radar has helped us a lot". Similar situations to Korean Air Flight 801 have been found in other plane crashes.
A- To test whether participants who had received a favor from another would be more likely to help this person than if they had not received a favor.
P- One participant and a confederate of the experimenter were asked to rate paintings. In the experimental condition the confederate left the experiment and returned after a few minutes with two bottles of coca cola. He had bought one for himself and one for the participant. In the control condition, the participant did not receive a coke. When all the paintings had been rated the experimenter left the room again. The confederate told the naive participant that he was selling raffle tickets for a new car and that the one who sold the most tickets could win $50. He then asked the participant if he would buy some tickets and said that even a small amount would help.
F- The participants in the experimental condition bought twice as many raffle tickets than participants in the control condition who had not received a favor first.
C- A follow up questinnaire asked if the participant liked the confederate in both conditions. There was not a significant differnt in the liking of the experimental group and control group, showing that reciprocity is the reason why the participants bought rattle tickets.
Martinez and Kesner (1991)
A- To investigate the role of neurotransmitter acetylcholine on memory, specifically memory formation
P- Rats were trained to go through maze and get to the end where they received food. After rats were able to do this, he injected the first group with scopolamine, which blocks acetylcholine receptor sites, the second group with physostigmine, blocks production of cholinesterase (does 'clean-up' of acetylcholine from synapse), and the third group was a control who weren't given injections.
F- Rats with the scopolamine injection were slower at finding way round maze and made more errors than control/physostigmine group, whereas the rats with the physostigmine injection ran faster compared to both groups and made fewer wrong turns.
C- Acetylcholine played an important role in creating a memory of the maze.
Newcomer et al. (1999)
A- To investigate whether high levels of the stress hormone cortisol interfere with verbal declarative memory
P- In order to investigate a possible link between cortisol and memory the researchers designed an experiment with three experimental conditions: A high level cortisol (160 mg) which produces blood levels similar to those seen in people experiencing a major stress event, a low level of cortisol (40 mg) which is similar to low stress event (surgical procedure), and finally placebo tablets which is a control group. All participants were asked to listen to and recall parts of a prose paragraph. This tested their verbal declarative memory. It is known that verbal declarative memory is often affected during longterm stress and the researchers knew from previous studies that cortisol could be involved in memory impairment.
F- The results indicated that high cortisol levels impaired performance in the memory task as they had the worst performance in verbal declarative memory.
C- According to the researchers, these results demonstrate a clear link between levels of cortisol and remembering.