Maguire, 2000 (Taxi Drivers) Flashcards
What does an MRI scan measure in the study?
Structure of the tissue of the brain.
What does MRI stand for?
Magnetic Resonance Imaging
What is the major function of the hippocampus?
Memory and Spatial Navigation.
Name the parts of the hippocampus.
- Front: Anterior
- Middle: Body
- Back: Posterior
Define Intracranial Volume (ICV).
Space within the skull- the bigger the ICV, the bigger the brain.
What is the aim of the study?
To demonstrate that the hippocampus is the region of the brain associated with spatial memory and navigation.
What is the method of the study?
Quasi experiment using correlation.
What is the IV in this study?
London black cab taxi driver or none taxi driver.
What is the DV in this study?
Hippocampal volume (measured using MRI scan).
Describe the participants.
- 16 London black cab taxi drivers
- Licensed drivers for more than 1.5 years (mean 14.3 years)
- Right-handed
- Mean age 44 (range 32-62)
- All healthy medical, neurological and psychiatric profiles.
Describe the control group.
- 50 healthy males
- Right handed
- Non taxi drivers
- Same age as other group
Why did Maguire exclude women?
To prevent any participant variables that could affect the DV other than the IV.
Describe the procedure.
Data was collected using MRI scans and then these scans were analysed using two techniques, Voxel-Based Morphometry (VBM) and Pixel Counting.
Describe how VBM was used.
The scans of 13 of the control group were used to produce an image “template” against which all scans were judged using VBM. It calculates the volume of an area, in this case grey matter (linked with neural connections) in the brain as measured by the structural MRI scan.
Describe how Pixel-Counting was used.
- Used to calculate hippocampal volume.
- Analysed by one “blind” person who counted the pixels produced by the MRI scan.
- Total hippocampal volume was calculated by adding up the pixels from each scan slice and multiplying it by the distance between adjacent slices. A correction was made for total ICV. The 16 taxidrivers were compared to 16 of the control group.
What were the results? (4)
- TD: Increased grey matter found in brains of taxi drivers (ONLY L&R hippocampi).
- TD: Increased L&R posterior hippocampi.
- NTD: More L&R anterior hippocampi.
- Total hippocampal volumes and ICV did not differ.
What was correlated?
Time spent being a taxi driver and hippocampal volume (posterior and anterior).
What were the results of the correlations? (2)
- Positive: Time spent as taxi driver and volume of RIGHT (only) posterior hippocampus.
- Negative: Time spent as taxi driver and volume of anterior hippocampus.
What does the study show?
Experience can alter the structure of the brain and shows plasticity. Nurture is influential.
What are the weaknesses of the method used?
- Lack of manipulation of IV- hard to draw out conclusions (difference could be because of a different factor).
- People with a larger hippocampal volume are the ones who choose to do “The Knowledge.”
- Scan data alone does not allow us to conclude the differences between two groups are due to experience.
What were the strengths of the method used?
- Correlation suggests strong relationship between length of time as TD and posterior hippocampal volume, allowing researchers to say that hippocampus increases with experience.
- Scan data and correlational analysis combine to give an overall picture.
What type of data was collected?
-Quantitative data: collected using MRI scans to prevent biases and demand characteristics. Gives a lot of detail.
At the time of the study VBM analysis was a relatively new technique so the well-established technique of pixel counting was also used as a measure hippocampal volume. What kind of validity does this give?
Concurrent validity
