Biological Area Flashcards
Strengths and weaknesses of biological area
Strengths - highly controlled (internal validity) - technical equipment - objective Weaknesses - ecological validity - reductionist
Sperry aim
Study functions of independent hemispheres
Investigate effect of deconnecting the hemispheres
Sperry research methods
Quasi experiment
IV of having a split brain was naturally occurring
Sperry sample
11 patients who had undergone plot brain surgery
From surgery in USA (opportunity)
Sperry sample strengths and weaknesses
Weaknesses Small 2 had undergone surgery 4/5 years ago so brain may have adapted since Epilepsy may cause results NOT surgery Strengths Separate hemispheres No other choice than opportunity
Sperry equipment
Tachistoscope Projector Fix action point Hand shield Objects on table
Sperry controls
Visual - one eye covered - stimuli presented 1/10th of a second - asked verbally Tactile - hands shielded from view - same task of picking up object and saying what it was - symbols, images, objects, fixation point, equipment
Overall results of Sperry
LH/RVF: responsible for language
RH/LVF: can communicate non-verbally but will not report seeing material verbally
Sperry ethics
Uphold Consent Deception Withdrawal Break Protection from harm Confidentiality
Sperry reliability
Internal:
Controlled, yes
External:
Not large enough to establish consistent effect, 11
Validity: Sperry
Internal, construct:
May not have been testing hemispheres, brain may have adapted since surgery
External, population:
Can be generalised to people with split brain surgery
External, ecological:
Visual tasks true to life, tactile not
Sperry ethnocentrism
USA specific area of surgery
Sperry links to debates
Nature/nurture
Reductionism/holding
Scientific/non scientific
Blakemore and Cooper aims
Investigate how being raised in a visually restrictive environment would affect the visual brain development of cats
- Compare behavioural consequences
- Compare neurophysiological effect in visual cortex
B & C research methods
Lab experiment
Independent measures
IV- stripes
Controlled environment- stripes, light exposure
B & C sample
2 kittens
B & C Procedure
First 2 weeks: - completely dark room Two weeks- five months: - cylinder for 5 hours everyday - wore large black collar so couldn’t see their body After five months: - well lit room with furniture - behaviour observed
B & C controls
Time in conditions Age Black collar Light exposure Stripes or horizontal lines
B & C initial behavioural results
- clumsy
- visual deficits
- navigate using touch
- normal pupillary reflexes
- no visual placing
- deficits disappeared after 10 hours-
B & C behavioural results after 10 hours
- now have visual placing
- startle reflex came back
- still clumsy
B & C behavioural results horizontal v vertical
Only startle with Perspex sheet with same lines exposed to when younger
Only chased a rod when same direction as lines exposed to when younger
Permanent
B & C neurophysiological results
Visual neutron optimal orientation
Neurons optimal based on line direction
B & C conclusions
Difference in kittens suggests neurons can change their preferred orientation according to the stimulation they receive, matching the ability of their brain to respond to the features in its visual input
B & C ethical upheld
Benefits can outweigh cost
Reduced harm- only used 2 kittens, smaller sample
B & C ethical issues
Pain & distress not minimised
Benefits may not outweigh costs- some permanent damage and information learned from this is not very applicable or useful
B & C reliability
Internal:
Lots of controls so is standardised and replicable
External:
2 cats not able to suggest consistent effect
Biology is universal so may not need larger sample
B & C validity
Internal: construct
Scientific results that show biological differences, can be sure to measure plasticity
Internal: concurrent
Can help to predict future behaviour
External: ecological
Very unlike any real life situation, not useful
External: population
Can only be generalised to certain species
B & C ethnocentrism
Culture isn’t relevant as it was done from birth
B & C link to debates
Nature/nurture Ethical considerations Psychology as a science Individual- situational Usefulness of research
Sperry procedure
Visual task:
Sat down 1 eye covered, stare at fixation point, image flashed 1/10 second
Asked to either name, draw or pick up object
Tactile:
Sat down hands shielded from view, pick up object 1 hand
Asked to either: name, point at or pick up object again
Sperry conclusion
Each side has own consciousness
Lateralisation of function
Maguire aims
- investigate differences in the brain (hippocampus) of London Taxi Drivers
- investigate function of hippocampus in spatial memory
- investigate plasticity of brain
Maguire research method
Quasi
Taxi driver IV naturally occurring
Maguire experimental design
Independent measures (matched groups
Maguire sample
32 altogether (all male, all aged 32-62, all right handed) Taxi drivers: - 16 males - licensed for at least 18 months - all healthy Control group: - 16
Maguire procedure
MRI scans converted into a picture where they measured volume of grey matter in hippocampus in two ways
1. Voxel based morphometry
- objective 3D measure of density calculated by a computer
2. Pixel counting
- 2D manual technique added up pictures from each slide
(Made unaware of which were taxi drivers)
Maguire controls
Sample (age, gender, right handed)
Maguire results
VBM analysis
- taxi drivers had increased grey matter volume on left and right side of posterior hippocampus but decreased in grey matter volume on anterior
Pixel counting found no difference
Findings from correlations analysis: if relationship between time as taxi driver and hippocampal volume
Length of time and volume of hippocampus had positive correlation with right posterior
Negative correlation with right anterior hippocampus
Maguire conclusion
Regional differences in brain structures of taxi drivers
Found brain plasticity- brain changes in response to demands of being a driver
Maguire anterior vs posterior functioning
Posterior is involved with previously learned material
Anterior is involved with new kearning
Maguire left and right hippocampus functioning
Right= mental maps Left= memories and events
Maguire validity
Internal: - EV such as gender and health controlled, MRI means no demand characteristics, no researcher bias as not told which were taxi drivers - concurrent (2 tests) External: - MRI not true to life - population (limited range in sample)
