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
16 right handed males, licensed cab drivers who
had passed 'the Knowledge'.
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.
50 right handed males, were selected from an MRI database
at the same centre in which the taxi drivers were scanned.
The age ranged from 32 to 62 years to match the general profile of the cab drivers.
The mean age and spread of the groups were similar.
Magnetic Resonance Imaging
Voxel-based morphology and pixel counting
Scientific methods of measuring the size of the brain.
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).
2) The data from the MRI scans
were correlated with how long the
cab driver had been licensed.
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.
Type of Data
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.
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.
On mean, the taxi drivers had a smaller anterior hippocampus
and a larger prosterior hippocampus than the control group.
No other differences were found in the
brains structure between the two groups.
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
"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
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.
(This strongly suggests that
the hippocampus can indeed
increase in size of time)
Usefulness of the study
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.
The small sample cannot be generalised to violent offenders of murderes because of their apparent differences in the brain.
People with pacemakers can not go in for an MRI scan as it the metal properties mess with the scanning process.
An MRI scan is not suitable for people with claustrophobia as the scan takes place in an inclosed space around the head/should area.
The interpretation of the MRI scan may be innacurate.
The pixel counting can be subject to human error causing data to be invalid.
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.
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.
As it is a snapshot study, it uses quantitative data meaning the results will showed clear correlations as to the two variables.
As the variables have not been manipulated the ecological validity of the study will be high.
High levels of control allow the results to be free from confounding variables and is therefore valid.
Applying these results to a broader context shows that the brain change after prolonged exposure to a constant stimulus/experience.
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.
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.
is part of the brain
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.
Nature VS Nurture
This research supports the
nurture side of the debate.
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.
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.
(IV) Independant Variables
If the participant was a taxi driver instead of a non-taxi driver.
(DV) Dependant Variable
The results of the MRI scan and, the Voxel-based morphology and pixel counting from each group.