Core Study - Maguire et Al

What was the aim of Maguire et al's study?

To investigate whether changes (plasticity) could be detected in the brains of London taxi drivers and to further investigate the functions of the hippocampus in spatial memory.

What was the hypothesis of Maguire et al's study?

If there were any differences in the brains of those who rely heavily on spatial navigational skills in their working life, then these differences would be found in their hippocampus.

Outline the sample used in Maguire et al's study.

- 16 healthy, right handed male licensed taxi drivers

- Mean age 44 (range 32-62 years)

- All participants licensed London taxi drivers for more than one and a half years and had completed the knowledge course

- Control group of 16 non-taxi drivers, matched on age range of taxi drivers

Name a limitation of the sample

Sample does not include women or left-handed people. This is a limitation as there are likely to be female London taxi drivers, and it may be that female navigational ability may be different from males due to stereotype views about female drivers. This means that any conclusions drawn will not be representative of all London taxi drivers and so the study cannot be generalised of the whole population.

What was the experimental method of the study?

Quasi experiment - IV was not manipulated by the experimenter as it already existed within participants.

Outline the procedure of the study

MRI scans were performed (by measuring soft tissue by exposing the brain to a strong magnetic field and radio waves to produce detailed pictures of the brain).

Name a strength and weakness of MRI scans

Strength - Objective, and provides quantitative data

Weakness - Only observes structure, doesn't tell active function of the brain

What methods did the researchers use to analyse the images produced from the MRI scans?

VBM - Measures density of grey matter in the brain. It provides a three-dimensional measurement of the volume of an area.

Pixel Counting - Measures volume of hippocampus. it provides a two-dimensional measurement of an area.

Outline the results of the VBM

VBM -

Taxi Drivers

-increase in grey matter in the left and right hippocampus. The increase was limited to the POSTERIOR.

Control Group

-They had a greater volume in the anterior

Outline the results of the Pixel Counting

Pixel Counting -

Taxi Drivers

-No difference in the overall volume of their hippocampus compared to the control group - but ti was different when comparing specific regions.

Both methods showed higher volume of grey matter in the POSTERIOR for TAXI DRIVERS, and higher volume of grey matter in the RIGHT ANTERIOR for NON-TAXI DRIVERS.

What did the results show?

- A negative correlation between the length of time as a taxi driver and the volume of grey matter in the right anterior - the longer the time spent as a taxi driver the less the volume of grey matter in the right anterior.

- A positive correlation between the length of time as a taxi driver and the volume of grey matter in the right posterior - the longer the time spent as a taxi driver the greater the volume grey matter in the right posterior.

What conclusions can be drawn from the study?

- The brain has plasticity - the ability to change to meet the demands of the environment. This is why there was a greater volume associated with the taxi drivers with the greater time spent as a taxi driver.

- The left and right sides of the hippocampus have different functions - the right side may be responsible for mental maps - this may be why the taxi drivers with more experience had a greater volume.

- Anterior Hippocampus - involved in previously learned information

- Posterior Hippocampus - involved in new environmental information

Discuss the reliability of the study

- Assessed by repeating the test

- Test the participants over a certain period of time ensuring that the test is an exact replication of the first assessment

- Participants could then be tested a week later using the same process

- This length of time should not allow natural changes in the brain to occur, therefore making it similar to those before

- The data produced would most likely be the same - MRI scans are very reliable as they are an independent, objective measurement

- By using a machine to gather data, researchers are able to:

-Rule out Human Error

-Rule out Investigator Bias

- Increase reliability

- Data produced from an MRI scan is quantitative, which makes it easier to analyse and to repeat the test.

Suggest some changes for the study

Use a wider sample e.g. stratified sample which means looking at a percentage of women who work as London taxi drivers, and including that proportion of females in the sample and to use left handed people.

Also, include other types of drivers e.g. comparing emergency drivers with public transport drivers and having an equal number of both for each group. This would make the study more generalised to a wider population as it will be more representative of drivers.

Strengths and Weaknesses of the Method

Strengths - The scan data along with the addition of the correlational analysis strongly suggests a relationship between the length of time the participants had been taxi drivers and the posterior hippocampus volume allows the researcher to suggest that the hippocampus increases with size as a result of navigational experience.

Also, quantitative data was collected through precise measuring equipment, increasing validity and this also eliminates demand characteristics.

Weaknesses - Differences between the groups may have been due to other factors