Physiological Psychology- Maguire et al. (2000)

Aim
1. Was to investigate whether changes could be detected in the brains of London taxi drivers and to further investigate the functions of the hippocampus in spatial memory.
Participants/Sample
1. 16 right handed males, licensed cab drivers who had passed 'the Knowledge'.
  Annotations:
  - To become a taxi driver you would have to study for at least 2 years and pass multiple tests, memorising all the streets of London, the routes that will get a customer to their destination the fastest and how to avoid roawork sites and so on.
  - The men in this study were between the age of 32 and 62 (with the mean age of 44). They had all been licenced for at least 18 months, ranging to 42 years (with the mean of 14.3 years).
  - Their average time spent in training for 'the Knowledge' was 2 years, ranging from 10 months to 3.5 years - some had studied continuously and some on a part-time basis.
  - All men were determined to have healthy, mental, neurological and psychiatric profiles.
2. 50 right handed males, were selected from an MRI database at the same centre in which the taxi drivers were scanned.
  Annotations:
  - The age ranged from 32 to 62 years to match the general profile of the cab drivers.
3. The mean age and spread of the groups were similar.
Methodology/Procedure
1. Quasi-Experiment
  1. Correlations
2. MRI Scan
  Annotations:
  - Magnetic Resonance Imaging
3. Voxel-based morphology and pixel counting
  Annotations:
  - Scientific methods of measuring the size of the brain.
4. 1) The 16 participants were subject to an MRI scan - the volume of the hippocampi was measured using the voxel based morphology (3D) and pixel counting (2D).
5. 2) The data from the MRI scans were correlated with how long the cab driver had been licensed.
6. 3) The 50 random scans were taken from the same MRI database that the cab drivers had been scanned at and the mean grey matter size of each group hippocampus was compared with each other.
Findings/Results
1. Type of Data
  1. Quantitative
2. A negative correlation between the the volume of grey matter in the anterior hippocampus and the length of time as a taxi driver was formed.
3. A positive correlation between the volume of the grey matter in the prosterior hippocampus and the length of time as a taxi driver was formed.
4. On mean, the taxi drivers had a smaller anterior hippocampus and a larger prosterior hippocampus than the control group.
5. No other differences were found in the brains structure between the two groups.
Conclusion
1. The results show evidence of a difference in both parts of the hippocampi between the cab drivers and the control group - The more experienced the cab driver, the larger his posterior hippocampus.
  Annotations:
  - "This suggests that 'proffesional dependance on navigational skills in licensed London taxi drivers is associated with the relative distribution of the grey matter in the hippocampus.' - Maguire et all, page 4402
2. The results of the correlational analysis suggest that some change could have possibly occurred since the taxi-drivers had qualified, the results indicating that the longer the cab driver had been employed, the larger his posterior hippocampus would be.
  1. (This strongly suggests that the hippocampus can indeed increase in size of time)
Usefulness of the study
1. The results of this study indicate that there is some 'plasticity' when it comes to the brain - the idea that ever past the main stages of the developmental stage, it can change and grow. In taxi drivers for instance, the posterior of the hippocampus expands with use, memorising the roads within the London area.
Weaknesses
1. Generalisability
  Annotations:
  - The small sample cannot be generalised to violent offenders of murderes because of their apparent differences in the brain.
2. Scanning Issues
  Annotations:
  - People with pacemakers can not go in for an MRI scan as it the metal properties mess with the scanning process.
  - (Ethics) An MRI scan is not suitable for people with claustrophobia as the scan takes place in an inclosed space around the head/should area.
3. Interpretation
  Annotations:
  - The interpretation of the MRI scan may be innacurate. The pixel counting can be subject to human error causing data to be invalid.
4. Extranuous Variable
  Annotations:
  - Extrenuous variables have not been taken into account. - A man may have become a taxi driver unknowingly as a result f an enlarged prosterior hippocampus.
Strengths
1. Quantitative Data
  Annotations:
  - The correlations are unlikely to be subject to bias.
  - Correlations help show if there is a negative, positive or any form of relation between the variables being researched.
2. Snapshot
  Annotations:
  - As it is a snapshot study, it uses quantitative data meaning the results will showed clear correlations as to the two variables.
3. Quasi-Experiment
  Annotations:
  - As the variables have not been manipulated the ecological validity of the study will be high.
4. Controls
  Annotations:
  - High levels of control allow the results to be free from confounding variables and is therefore valid.
5. Useful
  Annotations:
  - Applying these results to a broader context shows that the brain change after prolonged exposure to a constant stimulus/experience.
6. Valid
  Annotations:
  - The sample used is a group with specific knowledge and experience but are otherwise normal. This allowed us to see how those specific skills can develope and change in parts of the brain.
7. Sample
  Annotations:
  - Matched Pairs Design - The control sample was age matched, reducing the possibility of intelligence or age extranuous variables alowing the results to be more reliable.
Background
1. The hippocampus is part of the brain concerned with memory and spatial navigation.
2. The exact role of the hippocampus is not known, however it has been agreed by both neuroscientists and psychologists that is plays an important role in forming and storing new memories.
Arguments
1. Nature VS Nurture
  1. This research supports the nurture side of the debate.
  2. The initial analysis of the scan data could indicate that either innate differences in the hippocampal volume of those who become cab drivers and those who do not, or it could indicate changes as a result of experience.
  3. The correlation within this study shows that with experience, that there is a positive correlation with the experience of the cab driver and volume of the posterior indicating that is nurture which is evolving the brain - not nature.
Variables
1. (IV) Independant Variables
  Annotations:
  - If the participant was a taxi driver instead of a non-taxi driver.
2. (DV) Dependant Variable
  Annotations:
  - The results of the MRI scan and, the Voxel-based morphology and pixel counting from each group.

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Physiological Psychology- Maguire et al. (2000)

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	Created by Robyn Chamberlain about 10 years ago