Biological Studies Flashcards
HM - Milner (1966)
MRIs, Case studies, Localization, Plasticity
Aim: understand effects of surgery on HM
Procedure: longitudinal case study on HM
- HM had a bike accident at 7 & hurt part of his brain –> caused seizures
- to stop the seizures his hippocampus was removed at 27
- used method triangulation (IQ testing, direct observation, interviews, cognitive testing, MRIs to determine damage)
- found that HM has anterograde amnesia (cannot acquire episodic or semantic knowledge, but had capacity for working and procedural memory) –> temporal lobe and hippocampus had most damage
Results: hippocampus plays role in memory; human has ability to allocate role of memory to other brain parts (neuroplasticity)
Evaluation:
- + longitudinal (observed change over time)
- + method triangulation
- + high ecological validity
- + high ethical standards
- - not easily replicable
- - low internal valididty
- - retroperspective (only annectdotal data on ability before accident)
Maguire (2000)
fMRIs, localization, plasticity
Aim: to see whether the brains of London taxi drivers would be different as result of their detailed knowledge of the city
Procedure: correlational study with sample of 16 right-handed male london taxi drivers
- compared MRI scans with 50 other males using pixel counting and measuring density of grey matter
Results: hippocampus may change in response to environmental demands
- posterior hippocampi of taxi drivers significantly larger and anterior hippocampi significantly smaller
- volume of right posterior hippocampi correlated with time spent as taxi driver
Evaluation:
- + avoided researcher bias (blindly analyzed brain scans)
- + no low ecological validity (no actions in MRI scanner)
- - quasi-experiment –> no cause and effect relationship
- - sampling bias –> hard to generalize
Sharot et al (2007)
fMRIs, Localization
Aim: determine the potential role of biological factors on flashbulb memories
Procedure: quasi-experiment with sample of 24 recruited adults who were in NYC during 9/11
1. while in fMRI scanner, words presented to them with control ‘Summer’ and research condition ‘September’
2. After brain scan asked to rate memory’s vividness, accuracy, detail & emotion
Results: activation in amygdala was higher in participants who were closer to terrorist attack than when recalled summer events
–> correlates with people who had flashbulb memories
Evaluation:
+ + no demand characteristics
- - correlational (no cause and effect relationship)
- - low ecological validity (artificial –> fMRI)
- - no explanation for FBMs of events seen online
- - sampling bias –> difficult to generalize
Draganski (2004)
MRIs, Localization, Plasticity
Aim: see whether learning a new skill has an effect on the brain
Procedure: sample of 24 volunteers (ages 20-24),
1. allocated into 2 conditions: group 1 learns to juggle and group 2 has no training
2. MRI scans before, 3 months after training and 3 months after no training
Results: learning new skills has impact on the brain density
- brain densitiy significantly bigger in group 1 after after 3 months of training
- density shrank back after 3 months of no training
Evaluation:
- + pre-test/post-test design
- + experimental –> cause and effect relationship
- + control group
- - small sample size
- - low internal validity (field experiment, no control over variables)
Rogers & Kesner (2003)
NT: Acetylcholine/Scopolamine
Aim: determine role of acetylcholine in formation of (spatial) memory & retrieval
Procedure: sample of 30 rats
1. allocated in 2 conditions: either injected with scopolamine (blocks acetylcholine recepotor sites) or saline solution (placebo) into hippocampus
2. rats were made familiar with the maze
3. rats were set into a Hebb &Williams maze and assessed on # of errors made
Results: acetylcholine plays important role in consolidation of spatial memories
- scopolamine group took longer and made more mistakes in learning of maze but had **no issues with retrieval*
Evaluation:
- + placebo condition to avoid confounding variables
- + high internal validity (very controlled)
- - reductionist argument
- - animal research hard to generalize to humans
Atri et al (2004)
NT: Acetylcholine/Scopolamine
Aim: test the role of acetylcholine in memory formation by preventing proactive interference (old info prevents one from learning new knowledge)
Procedure: sample of 28 english undergrads, repeated measures
1. split into three groups: no injection, glycopymolate (agonist of acetylcholine RS) or scopolamine (atagonist)
2. read 18 related and 18 unrelated word pairs (robber-jail/stereo-fudge)
2. tested for recall by giving 1st word of the pair
3. after 30mins new list with overlapping and non-overlapping pairs
Results: acetylcholine plays important role in memory formation
- scopolamine group could not recall as many words in overlapping pairs as other conditions
Evaluation:
- + high reliability (easily replicable)
- + high internal validity (very controlled)
- + prevented recency effect
- - low ecological validity (artificial)
Wedekind (1995)
Pheromones, Evolutionary Psychology
Aim: to determine whether one’s MHC would affect mate choice
Procedure: sample of approx. 100 students
1. men were asked to wear t-shirt for two nights (controlled for perfumes, detergent & other smells)
2. women asked to rate smells of 7 shirts (controlled for nasal mucous and smell sensitivity)
3. three shirts from men with similar MHC, three with dissimilar MHC, and one control shirt
Results: MHC may influence mate choice
- body odours more pleasant when they differed from women’s own MHC
Evaluation:
- + high reliability (succesfully replicated)
- - reductionist (ignores sociocultural and cognitive factors)
- - minimized demand characteristics (double-blind experiment)
- - sampling bias (not representative in age and culture)
MHC: important gene for immune system; creates our personal smell
Caspi et al (2003)
Kinship studies, epigenetics & depression
Aim: to determine whether functional change in 5-HTT gene is linked to higher/lower risk of depression
Procedure: sample of 850 NZlanders, age 26
1. divided into 3 groups based on alleles: G1had 2 short alleles, G2 had 1 long 1 short alleles and G3 had 2 long alleles
2. asked to fill questionnaire on stressful life events & assessed for depression
Results: gene’s interaction with stressful life events increased likelihood of depression
- 1+ short allele demonstrates more symptoms of depression in response to stress
Evaluation:
- + holistic approach (acknowledges interaction of biological & environmental aspect)
- - low reliability (replication apparently not possible)
- - correlational (no cause effect relationship)
- - assumption that serotonin causes depression
- - gene alone cannot cause depression
Kendler et al (2006)
Kinship studies, epigenetics & depression
Aim: to determine the role that genetics plays in major depressive disorder
Procedure: sample of 15K swedish twins
1. participants interviewed and assessed for major depressive disorder in accordance with DSM-IV
Results: depression somewhat heritable, but environment and stress play a big role (diathesis stress theory)
- researchers estimated from condordance rates in mono- and dizogotic twins that heritability of depression is roughly 38%
- rate was higher in females
- (MZ male - 31%: MZ female - 44%: DZ Males - 11% DZ females - 16%)
Evaluation:
- + High generalizability
- + Adhered to ethical guidelines
- - No cause & effect relationship
- - Self reported data, unreliable results
