biological Flashcards
maguire et al (2000)
aim
- investigate whether neuroplasticity occurs in London taxi drivers who need to memorize the area to get their license
maguire et al (2000)
procedure
- a sample of 16 healthy right handed london taxi drivers
- had their brains scanned using an MRI
- their brains were compared with non taxi drivers with the same characteristics
maguire et al (2000)
results
- the posterior (rear) of the hippocampus was significantly bigger in taxi drivers
- the anterior (front) of the hippocampus was larger in the control group
- positive correlation between years of experience being a taxi driver and the size of the posterior hippocampus
maguire et al (2000)
conclusion
- hippocampus is the region of the brain associated with memory
- posterior hippocampus is related to spatial memory and navigation
- taxi drivers have a mental map which causes the increase
maguire et al (2000)
evaluation
- supports neuroplasticity and localization of function
- can be easily replicated, lab setting
- statistical analysis of data
- no ethical concerns
- controlled, age, gender, occupation etc
- people that have a larger posterior hippocampus more likely to do a job involving navigation
- not generalizable, women, ethnicities, other occupations
draganski et al (2004)
aim
- investigate whether structural and functional changes happen in the brain after learning a new motor skill
draganski et al (2004)
procedure
- MRI scans, see changes participants learning to juggle
- randomly allocated 2 groups, juggling and non juggling (control)
- brains scanned 3 times, before learning, 3 months after learning, 3 months after stopping juggling
- scans compared to control group of non jugglers
draganski et al (2004)
results
- before learning to juggle 1st scan, no difference
- group of jugglers second scan, 2 areas of the brain significantly different size than control
- third scan, difference became smaller
draganski et al (2004)
conclusion
- watching balls and learning to move in response strengthened neural connections in the brain responsible for the activity
- temporary, rely on continuing the activity or else neural pruning took place
draganski et al (2004)
evaluation
- supports neuroplasticity and localization of function
- field experiment, juggling occurred in natural conditions
- random allocation to groups, standardization of measurement, high internal validity
- well controlled, able to be replicated
harlow (1849)
aim
- investigate how serious damage to the left frontal lobe impacts behaviour
harlow (1849)
procedure
phineas gage was a railroad worker who suffered a severe accident
- metal rod went through his skull almost fully destroying his left frontal lobe
- harlow observed gage’s behaviour after the accident and interviewed people who knew him both before and after
harlow (1849)
results
- gage’s personality changed dramatically due to the brain damage
- before he was responsible and capable
- after he was highly emotional and unable to control impulses
- incapable of following through with plans
- began to behave inappropriately using vulgar language, acting violent and potentially touching children
harlow (1849)
conclusion
- frontal lobe plays an important role in personality
- impacts goal setting, self regulation and following social norms
harlow (1849)
evaluation
- supports localization of function
- not possible to replicate this study so not generalizable
- gage’s behaviour was inconsistent and there is unclear information
- don’t know that much information about his personality before the accident so we don’t know how much his personality actually changed
rosenzweig and bennet (1961)
aim
- investigate neuroplasticity in rats
rosenzweig and bennet (1961)
procedure
- rats were randomly placed in one of two different environments
- one was enriched environment (EE) where rats played with toys, games and a maze
- other was the deprived environment (DE) where they were alone in a cage with no toys
- rats either spent 30 or 60 days in their enclosures and were then killed to examine the changes in their brains
rosenzweig and bennet (1961)
results
- rats in the EE had a heavier frontal lobe and thicker cortex in comparison to rats in the DE
- a thicker cortex means more neural connections
- frontal lobe is important in decision making and self control
rosenzweig and bennet (1961)
conclusion
- being in a more stimulating environment causes new connections to form which changes brain structure
rosenzweig and bennet (1961)
evaluation
- supports neuroplasticity
- lab experiment so extraneous variables were controlled
- cause and effect relationship as rats were randomly chosen for each group
- questionable if rats apply to humans even though we have genetic similarity
- ethical issues as the rats were killed
antonova et al (2011)
aim
- investigate the role of the neurotransmitters acetylcholine and scopolamine on spatial memory
antonova et al (2011)
procedure
- participants 20 men, average age 28
- randomly allocated scopolamine injection or saline injection (placebo)
- brains scanned using fMRI scans whilst finding their way around a VR maze, mainly looking at the hippocampus
- after one trial participants returned 1 month later injected with whichever solution they didn’t recieve before and rescanned
- double blind
antonova et al (2011)
results
- scopolamine reduced activity in the hippocampal area
- scopolamine injection group made more errors than placebo
antonova et al (2011)
conclusion
- scopolamine decreases acetylcholine action in the brain, acetylcholine is associated with spatial memory
antonova et al (2011)
evaluation
- randomized groups that experienced both conditions, double blind, well controlled
- cause and effect relationship
walderhaug et al (2007)
aim
- investigate the role of serotonin on mood regulation and impulsivity in men vs women
walderhaug et al (2007)
procedure
- 83 healthy participants, acute tryptophan depletion, decreases serotonin levels in the brain
- randomized, double blind experiment
- behavioural measures were taken of impulsivity and mood
walderhaug et al (2007)
results
- men exhibited more impulsive behaviour, did not alter mood
- women mood worsened, more cautious behaviour, linked with depression
- women, impacted serotonin transportation in the synapse
walderhaug et al (2007)
conclusion
- women and men appear to respond differently to neurochemical changes
walderhaug et al (2007)
evaluation
- small number of participants
- results may not be generalizable to a wider range of people
- able to be replicated
martinez and kesner (1991)
aim
- investigate the role of the neurotransmitter acetylcholine in spatial memory formation
martinez and kesner (1991)
procedure
- rats trained to run in a maze
- randomly divided into groups
- group 1: injected with scopolamine, blocks acetylcholine receptor sites, reduces availability of acetylcholine
- group 2: injected with physostigmine, increases availability of acetylcholine
- group 3: control group, no injections
martinez and kesner (1991)
results
- group 1 rats scopolamine and less acetylcholine, more mistakes and slower in comparison to group 2 physostigmine and more acetylcholine
martinez and kesner (1991)
conclusion
- the neurotransmitter acetylcholine increases spatial memory
martinez and kesner (1991)
evaluation
- able to replicate
- reliable, well controlled
rogers (2011)
aim
- investigate the role that serotonin plays in perceiving emotional intimacy
rogers (2011)
procedure
- participants were 40 healthy male adults
- half the participants received a drink with tryptophan in it which increases levels of serotonin and the other half had a drink without it
- after participants were given photos of couples and asked to rate how “intimate” and “romantic” the couples seemed
rogers (2011)
results
- participants with lower serotonin (did not have tryptophan) rated the couples less intimate and romantic than the other group
rogers (2011)
conclusion
- serotonin plays a role in how humans judge the closeness of people’s relationships
- possible implications of depression as they perceive their relationships as less than they are
rogers (2011)
evaluation
- casual relationship between the levels of serotonin and ratings of relationships
- rating closeness is not something people would do in real life, low ecological validity
- only in one culture (british) findings should be replicated on a bigger scale
carré et al (2016)
aim
- investigate the impact of personality and testosterone on aggressive behaviour
carré et al (2016)
procedure
- 100+ healthy male participants randomly allocated 2 groups
- personality regarding dominance and impulsivity were assessed using questionnaires
- group 1: testosterone injection
- group 2: placebo
- decision making game designed to test aggression after social provocation within the game by a partner (actually the computer)
carré et al (2016)
results
- only increase in testosterone was not enough to provoke aggression
- more aggression = additional testosterone, low impulse control, high dominance
- just additional testosterone ≠ aggression, need traits
carré et al (2016)
conclusion
- increased levels of testosterone are not the only reason for aggressive behaviour but also personality
carré et al (2016)
evaluation
- only men
- double blind, reliable, well controlled
albert (1986)
aim
- investigate the impact of testosterone on aggression in alpha male rats
albert (1986)
procedure
- identified alpha males by size and strength, measured aggression levels
- randomly divided alpha male rats into 4 groups
- group 1: castration
- group 2: castration, implant empty tubes
- group 3: castration, implant tubes of testosterone
- group 4: cut open and sewn up (control)
- measured change in aggression levels before and after surgery
albert (1986)
results
- 1 and 2 rats whose testosterone levels were diminished displayed less aggression
- 3 and 4 rats testosterone levels remained the same so there was no significant change in behaviour
- 2 had testosterone replaced after, aggression increased
albert (1986)
conclusion
- testosterone plays an important role in aggression and dominance
- higher testosterone = higher levels of aggression and dominance
albert (1986)
evaluation
- well controlled variables, lab experiment, replicability, reliable
- ethical issues experimenting on animals
wedekind et al. (1995)
aim
- investigate whether women prefer male odour with a different MHC than their own
wedekind et al. (1995)
procedure
- 44 male students wear the same T-shirt 2 consecutive nights, kept in plastic bag between the nights, remain as odour free as possible
- mean age 25, all participants classified immune system similarity via a blood test,
- after wearing shirt, 49 female students asked to rate each shirt/6 for pleasantness and odour intensity, through a hole in a cardboard box
- 3 shirts MHC similar, 3 shirts MHC dissimilar
wedekind et al. (1995)
results
- women more pleasant MHC dissimilar, opposite if on oral contraceptive pill
wedekind et al. (1995)
conclusion
- suggests the existence of a human pheromone to assist in the role of mating
- birth control mimics pregnancy, more likely to look for similar familial to support child vs better immune system for future child dissimilar mate
wedekind et al. (1995)
evaluation
- low ecological validity, act on scent?
- replicable, well controlled
doty (2010)
- no scientific definition about what a human pheromone actually is
- human pheromones have not been chemically isolated
- shouldn’t assume because it happens in animals it also happens in humans
-multiple chemicals in the environment at the same time, why would one more from a human influence behaviour in other members of the same species
savic et al (2009)
aim
- investigate whether human pheromones exist and how they impact our brains
savic et al (2009)
procedure
- researchers exposed participants (24 men and women) to the smell of two chemicals
- chemicals were almost identically to naturally produced sex hormones, testosterone and estrogen
- as participants smelled the chemicals their brains were scanned with a PET machine
savic et al (2009)
results
- hypothalamus became activated in men when they smelled the female hormone and in women when they smelled the male hormone
- hypothalamus is linked to sexual behaviour and not normally activated by other smells
savic et al (2009)
conclusion
- suggests sex pheromones exist in humans and they influence sexual behaviour
savic et al (2009)
evaluation
- well controlled lab experiment showing a causal relationship between the chemicals (IV) and activity in the hypothalamus (DV)
- small number of participants, needs to be replicated to confirm
- measured changes in brain activity not actual behaviour
- would these people act on the brain activity? unknown
francis et al (2003)
aim
- investigate how the interaction between genes and the environment impacts how rats nurture their offspring
francis et al (2003)
procedure
- mothers separated into groups of either high licking or low licking
- licking in rats is a sign of care and affection
- after 12 hours of being born rats with high licking mothers were switched to rats with low licking mothers and vice versa
francis et al (2003)
results
- rats raised by high licking mothers were less stressed and grew up to be high licking mothers too even if their biological mother was a low licker
- lost the methyl groups around high licking causing that gene to be turned on
francis et al (2003)
conclusion
- being in a loving environment impacts genes
- those epigenetic changed genes are passed on to the next generation
francis et al (2003)
evaluation
- well controlled experiment
- use of animals is less unethical, switching human babies in real life?
- easier to study across generations due to rats and not humans
- done on rats so not sure generalizable to humans
suderman et al (2014)
aim
- investigate the impact of childhood abuse on DNA
suderman et al (2014)
procedure
- 45 year old men, blood DNA analyzed
suderman et al (2014)
results
- increased methylation of the gene PM20D1 in the sample who suffered abuse
- associated with control over eating habits, greater prevalence of obesity
suderman et al (2014)
conclusion
- environmental trigger (abuse) can contribute to the methylation of PM20D1 which contributes to a persons food intake
- suggests interactions between genes and environmental influences can predispose a person to behave in a certain way
suderman et al (2014)
evaluation
- only 45 year old men, lacks generalizability
- lots of extraneous variables
kendler et al (2006)
aim
- investigate concordance rates of MDD in monozygotic and dizygotic twins
kendler et al (2006)
procedure
- swedish national twin registry, 15,000+ complete twin pairs
- phone interviews over 4 years to diagnose MDD using the DSM-4 or prescription for antidepressants
kendler et al (2006)
results
- average concordance rate across all twins 38%
- no correlation between number of years lived together, suggests heritability
- monozygotic female 44%, dizygotic female 16%, men lower for both
kendler et al (2006)
conclusion
- environmental factors influence MDD as concordance rates for MZ twins would have been higher
- MZ twins concordance higher than DZ, genes still play a role
- heritability higher in women than men
kendler et al (2006)
evaluation
- large sample size
- only swedish people, generalizability?
mcgue et al (2000)
aim
- investigate the genetic and environmental influences on adolescent addiction to tobacco and marijuana
mcgue et al (2000)
procedure
- 626 pairs of twins born in the same year
- interviewed about their history and experience of tobacco (legal) and marijuana (illegal), drug use, home life and a questionnaire
mcgue et al (2000)
results
- slight heritability for marijuana, no significant difference between men or women
- tobacco 40-60% heritability
- participants that took drugs regularly, part of family life, parents other members, normal home environment
mcgue et al (2000)
conclusion
- environment appeared to be more influential in determining drug use than genetic inheritance
mcgue et al (2000)
evaluation
- extraneous variables
- all born in the same year, generalizability?
gottesman and goldsmith (1994)
aim
- find the concordance rate of juvenile delinquency in monozygotic twins vs dizygotic twins
gottesman and goldsmith (1994)
procedure
- studied 85 sets of young twins
- looked at criminal conviction records
gottesman and goldsmith (1994)
results
- the concordance rate of juvenile delinquency in MZ twins was 0.91 (91%)
- when compared to 0.73 (73%) for DZ twins.
- if one identical twin broke the law, there was a 91% chance the other twin had
- For DZ twins, this dropped to 73%.
gottesman and goldsmith (1994)
conclusion
- suggests genetics is a factor, if behaviour was because of environmental factors, we would expect closer or identical rates of concordance between MZ and DZ twins.
- they’re higher for MZ twins, we know genetics is a factor but since it’s not 100% for MZ twins, it’s not the only factor.
gottesman and goldsmith (1994)
evaluation
- high ecological validity
- shows nature has a role in criminal activity
- can’t be sure of the environment they grew up in, extraneous variables