SAQ - studies

Question 1

background for Milner’s H.M.

Answer 1

• longitudinal case study
• HM hit by a bike when he was 7 -> serious brain injury
• epileptic attacks began at 10, assumed to be connected with accident
• frequent seizures at 27 to a point where he couldn’t lead a normal life, no medications helped -> consent of HM & his family, neurosurgeon Dr. Scoville performed an experimental surgery of removing tissue from medial temporal lobe (including hippocampus) on both sides of HM’s brain

Question 2

aim for Milner’s H.M.

Answer 2

better understand the effects that the surgery had had on patient HM

Question 3

procedure for Milner’s H.M.

Answer 3

Dr. Milner used method triangulation:
- Psychometric testing: IQ testing
- Direct observation of behaviour
- Interviews with both HM and with family members
- Cognitive testing: Memory recall & learning tasks
- MRI scan later to determine the extent of the damage done to HM’s brain

Question 4

result for Milner’s H.M.

Answer 4

• IQ test: no general intellectual impairment
• retrograde amnesia right after surgery -> eventually diminished
• mainly suffered from anterograde amnesia: unable to remember the faces of people he met after the operation
• asking what he just had for lunch -> could not remember
• could not acquire new episodic knowledge
• could not acquire new semantic knowledge (episodic & semantic: declarative memory)
  
  • suggests that removed brain structures are important for the transfer of information from short-term to long-term memory
• cognitive map test: could draw picture of floor plan of his new home
  
  • this memory type (implicit memory) is not encoded the same way as declarative memory
• able to carry on normal conversation, recall number 584 15 minutes later by constant rehearsal -> had capacity for working memory
  
  • short-term memory is not stored in the hippocampus
  • wasn’t able to recall the number after the task was over
• knew how to mow a lawn, improvement in star mirror-drawing task -> procedural memories (implicit memory) were well maintained
  
  • never remembered learning the star drawing skill
• able to retain some memories for events that happened long before his surgery -> had long-term memory
  
  • medial temporal region is not the site of permanent storage but rather plays a role in the organization and permanent storage of memories elsewhere in the brain
• Corkin in 1992 & 2003 did MRI scan of HM’s brain to see the extent of damage -> parts of temporal lobe including hippocampus had the most damage
  
  • explains the problem of transferring short-term memory to long-term memory as hippocampus is the area where the neurotransmitter acetylcholine is believed to play an important role in learning and formation of memories
• longitudial case study: Dr. Milner studied HM until he died in 2008, for over 50 years
• holistic, retrospective, cannot be replicated, high ecological validity

Question 5

background for Draganski’s juggling study

Answer 5

• experimental field study

Question 6

aim for Draganski’s juggling study

Answer 6

to see whether learning a new skill (juggling) would have an effect on participants’ brain

Question 7

procedure for Draganski’s juggling study

Answer 7

• participants: 24 volunteers between the ages of 20 and 24, 21 females & 3 males
  
  • were non-jugglers at the start of the study
  • had MRI scan at the start -> served as base rate for grey matter & brain structure
• participants randomly allocated into one of two conditions: jugglers (12) / non-jugglers (12)
  
  • those in juggling condition: were taught a 3-ball cascade juggling routine, asked to practice the routine & notify researchers when they had mastered it -> second MRI scan -> told not to juggle -> final MRI scan 3 months later
  • those in non-juggling condition: served as control group
• used Voxel-based Morphometry (VBM) to analyze the MRI scans to determine if there was a significant difference in neural density (grey matter) in the brains of jugglers vs. non-jugglers

Question 8

result of Draganski’s juggling study

Answer 8

• baseline scans: no significant regional differences in grey matter between two conditions
• end of first part of study: jugglers showed significantly larger amount of grey matter in the mid-temporal area in both hemispheres (associated with visual memory)
  
  • appears that juggling relies more on visual memory than procedural memory
• 3 months after participants stopped juggling: amount of grey matter in these parts of brain decreased
• no change over the duration of study in non-juggling group

Question 9

background for Antanova’s anera task injection study

Answer 9

true experiment

Question 10

aim for Antanova’s arena task injection study

Answer 10

to see whether scopolamine affects hippocampal activity in the creation of spatial memory

Question 11

procedure for Antanova’s arena task injection study

Answer 11

• sample of 20 healthy male adults with mean age of 28 years old
• used double blind procedure: participants were randomly allocated into one of two conditions & injected with either scopolamine or placebo 70 -90 minutes before experiment
• participants put into fMRI -> scanned while playing “Arena task” (complex virtual reality game in which researchers observe participants’ ability to create spatial memory)
• goal for participants: navigate around an “arena” to reach a pole
  
  • after learning the pole’s location -> blank screen for 30 seconds while participants were told to actively rehearse how to get to the pole
  • when area reappears: participants at new starting point, need to use their spatial memory to determine how to get to the pole
• participants were first trained in the game to make sure they were comfortable with using joystick & they understood the game -> took part in experiment
• participants’ brain activity was measured for 6 trials
• participants returned after 3-4 weeks and redid the test, receiving the opposite treatment to the original study <- repeated measures design (eliminates effect of participant variability)

Question 12

result of Antanova’s arena task injection study

Answer 12

• when participants were injected with scopolamine, they demonstrated a significant reduction in activation of hippocampus compared to when they received a placebo
  
  • acetylcholine could play a key role in encoding of spatial memories in humans
  • higher error rate in scopolamine group but no significant difference
  • significant difference in activity in hippocampus
• study was counter-balanced: some did scopolamine condition first while others did placebo condition first -> controls for researcher bias
• during debriefing: several participants expressed that they felt stressed (bc of injection of unfamiliar drug / fMRI enclosure) -> could’ve affected the working of hippocampus since stress may interfere with memory encoding

Question 13

background for Newcomer’s cortisol pill study

Answer 13

true experiment

Question 14

aim for Newcomer’s cortisol pill study

Answer 14

investigate whether high levels of stress hormone cortisol interfere with verbal declarative memory

Question 15

procedure for Newcomer’s cortisol pill study

Answer 15

• all participants were employees/students at Washington University Medical Center
  
  • given clinical interview with a physician -> excluded from sample if they were pregnant, had history of mental illness, had suffered from head trauma or had suffered from illness that had been treated with corticosteroids
• double blind laboratory experiment: neither researcher doing the study nor participants know the specific type of treatment each participant receives until the experiment is over
• participants were matched for gender & age to one of three conditions:
  
  • condition 1: high level of cortisol -> given a tablet containing 160mg of cortisol on each day of the four-day experiment
    
    • this dose of cortisol produces blood levels similar to those seen in ppl experiencing major stress event
  • condition 2: low level of cortisol -> given a table containing 40mg of cortisol per day
    
    • this dose is similar to amount of cortisol circulating in the bloodstream of ppl undergoing minor surgical procedures
  • condition 3: placebo group -> given placebo tablets, done to have a control group
• all participants were asked to listen & recall a prose paragraph
  
  • each day participants were given different piece of prose with same level of difficulty
  • tested 3 times
• all participants were first tested before taking any cortisol -> no significant difference between groups
  
  • important control to make sure that at baseline, individual differences won’t be a confounding variable for the study
• participants were tested one day after taking the pill & then again four days later, another test six days later to ensure that there were no long-term effects of treatment on participants

Question 16

results for Newcomer’s cortisol pill study

Answer 16

• high cortisol levels impaired performance in memory task
  
  • participants who received highest level of cortisol showed worst performance in verbal declarative memory
• researchers verified that the effect wasn’t permanent: performance of high cortisol condition participants returned to normal after they stopped taking the hormone tablet
• according to researchers, these results demonstrate a clear link between level of cortisol & remembering
  
  • appears that high levels of cortisol interfered with recall of prose passage
• no statistical difference between low dose & placebo groups on any day of testing
  
  • researchers claimed that paragraph performance increased over time for placebo & low dose groups bc of practice effects of procedural learning

Question 17

background for Wedekind’s sweaty T-shirt experiment

Answer 17

quasi experiment

Question 18

aim for Wedekind’s sweaty T-shirt experiment

Answer 18

to determine whether one’s MHC would affect mate choice

Question 19

procedure for Wedekind’s sweaty T-shirt experiment

Answer 19

• sample made up of 49 female & 44 male students from University of Bern
  
  • each participant was typed for their MHC & wide variance of MHC was included in the sample
  • noted if women were taking oral contraceptives
  • researchers suggest that students probably didn’t know each other as they were from different courses
    
    • women from bio & psych
    • men from chem, physics & geography
• men were asked to wear T-shirt for 2 nights & keep T-shirt in open plastic bag during the day
  
  • given perfume-free detergent to wash clothes & bedclothes, perfume-free soap for showering
  • asked not to use any deodorants/perfumes, refrain from smoking tobacco/drinking alcohol, avoid all spicy foods, not engage in any sexual activity
• two days later, women were asked to rank the smell of 7 T-shirts, each in cardboard box with smelling hole
  
  • women were tested whenever possible in 2nd week after beginning of menstruation, as they appear to be most odor-sensitive at this time
  • asked to prepare themselves for the experiment by using nose spray for 14 days before experiment to support regeneration of nsal mucous membrane if necessary & to prevent colds or flu
  • each woman was given a copy of the novel Perfume to sensitize their smell perception
• 3 of 7 boxes contained T-shirts from men with MHC similar to women’s own, 3 contained T-shirts from MHC dissimilar men & 1 contained unworn T-shirt as control
  
  • alone in a room, every woman scored odors of T-shirts for intensity (range 0-10), pleasantness & sexiness (range 0-10, 5=neutral)

Question 20

results for Wedekind’s sweaty T-shirt experiment

Answer 20

• women scored male body odors as more pleasant when they differed from their own MHC than when they were more similar
  
  • difference in odor assessment was reversed when women rating the odors were talking oral contraceptives
  • suggest that MHC may influence human mate choice
• study seems to support an evolutionary argument for mate selection in humans
• reductionist: over-simplifies behavior of human mate selection by bringing it down to MHC, ignoring cognitive & sociocultural factors
• double-blind experiment: neither the researchers nor participants were aware of which T-shirt they were being exposed to at any point in the study

Question 21

background for Caspi et al (New Zealand)

Answer 21

quasi experiment

Question 22

aim for Caspi et al (New Zealand)

Answer 22

• to determine whether there’s evidence for gene-environment interaction (G x E) for mutation of 5-HTT
• to assess effect of 5-HTT gene on depression

Question 23

procedure for Caspi et al (New Zealand)

Answer 23

• Caspi and his team looked at sample of 847 New Zealand 26-year-olds
  
  • all born between April 1st, 1972 & March 31st, 1973 in Dunedin, New Zealand
  • as part of Dunedin study, they had been assessed for mental health on every-other-year basis until they were 21
• divided into 3 groups based on their 5-HTT alleles:
  
  • group 1: two short alleles
  • group 2: one short & one long allele
  • group 3: two long allele
  • mutation of 5-HTT gene has shorter alleles
• participants were asked to fill in “stressful life events” questionnaire which asked them about frequency of 14 different events (financial, employment, health, relationship stressors etc) btwn age of 21 and 26
• participants were assessed for depression

Question 24

results for Caspi et al (New Zealand)

Answer 24

• participants who had inherited one or more short versions of allele demonstrated more symptoms of depression & suicidal ideation in response to stressful life events
  
  • simply inheriting the gene wasn’t enough to lead to depression, but genes’ interaction with stressful life events increased one’s likelihood of developing depression
• made assumption that serotonin is related to depression
  
  • some individuals may have depressive symptoms that are unrelated to depression
• information about life-events was self reported -> it may be salience of negative life events which plays role in depression
• acknowledges interaction btwn both biological & environmental factors in depression -> holistic

Question 25

background for Kendler et al. twin study

Answer 25

quasi-experiment

Question 26

aim for Kender et al. twin study

Answer 26

to investigate 3 questions:
1) would the data suggested by past studies, 35-45% heritability of major depression, be true in a large Swedish sample?
2) are there significant gender differences in heritability of major depression?
3) is there evidence that genetic & environmental factors in major depression differ over time?

Question 27

procedure for Kendler et al. twin study

Answer 27

• sample: 15,493 complete twin pairs listed in national Swedish Twin Registry
  
  • twins born between 1886 and 1958
  • only twins whose zygosity could be verified were used in study
• researchers used team of trained interviewers to carry out telephone interviews to gain data
  
  • interviews were carried out between March 1998 & Jan 2003
  • interviewers assessed lifetime major depression using modified DSM-IV criteria
  • 8056 twins met criteria for diagnosis of major depression at some point in their life
  • 322 twins voluntarily discussed history of antidepressant treatment
• researchers also asked questions about twins’ “shared environment” (when they were living in the same household) & “individual-specific environment” (adult personal life events that may make members of the twin pair more susceptible to depression)

Question 28

results for Kendler et al. twin study

Answer 28

• concordance rate for major depression is significantly higher in women than men
• correlations significantly higher in monozygotic than in dizygotic twins
• no correlation between number of years twins had lived together & lifetime major depression
• estimated heritability of major depression: 0.38
• no significant difference was seen in roles of genetics & environmental factors in major depression in three cohorts spanning birth years 1900-1958
  
  • even when they split the entire cohort into pre & post WWII, there was no significant difference
• suggests that heritability of major depression is higher in women than in men
• suggests that some genetic risk factors for major depression are sex-specific
• correlational, no cause & effect relationship can be determined
• information about life-events & depressive symptoms was self reported -> difference could arise if men are less reliable in their reporting of lifetime major depression than women
• interviewers accepted diagnoses made by clinicians when it was reported by interviewee <- clinical diagnoses are not highly reliable, questionable validity