Summary of the Core Study
Maguire: Navigation-related structural change in the hippocampi of taxi drivers
Background: the hippocampus helps spatial memory, in the form of navigation. From previous studies, it was impossible to know whether differences in brain anatomy are predetermined (nature), or whether the brain is susceptible to plastic changes, in response to environmental stimulation (nurture). Taxi drivers undergo extensive training, known as ‘The Knowledge’ and therefore make an ideal group for the study of spatial navigation.
Aim: To investigate if structural changes could be detected in the brain of people with extensive experience of spatial navigation.
Sample: Experimental group = 16 right-handed male London taxi drivers participated; all had been driving for more than 1.5 years. Control group = 50 healthy right-handed males who did not drive taxis were included for comparison. The mean age did not differ between the two groups.
Method: Natural experiment: IV: London Taxi driver or not. DV: Structure and volume of hippocampi. Structural MRI scans were obtained.
Results:
Conclusion: The results provide evidence for structural differences between the hippocampi of London taxi drivers and control participants, therefore suggesting that extensive practice with spatial navigation affects the hippocampus.
Evaluation:
Background: the hippocampus helps spatial memory, in the form of navigation. From previous studies, it was impossible to know whether differences in brain anatomy are predetermined (nature), or whether the brain is susceptible to plastic changes, in response to environmental stimulation (nurture). Taxi drivers undergo extensive training, known as ‘The Knowledge’ and therefore make an ideal group for the study of spatial navigation.
Aim: To investigate if structural changes could be detected in the brain of people with extensive experience of spatial navigation.
Sample: Experimental group = 16 right-handed male London taxi drivers participated; all had been driving for more than 1.5 years. Control group = 50 healthy right-handed males who did not drive taxis were included for comparison. The mean age did not differ between the two groups.
Method: Natural experiment: IV: London Taxi driver or not. DV: Structure and volume of hippocampi. Structural MRI scans were obtained.
- Voxel based morphology was then conducted on the scans. This gave a 3D measurement of the density of grey matter.
- Then Pixel counting which gave a 2D measurement of volume. 24 ‘slices’ (images) of the brain were taken for this - 24 focused on the hippocampus.
- A correlational analysis was also conducted to investigate whether time as a taxi driver correlated with the volume of the hippocampus.
Results:
- VBM - there was more grey matter in taxi drivers’ posterior hippocampus than non-taxi drivers but less in their anterior.
- Pixel counting - there was no difference in volume between taxi-drivers’ and non-taxi drivers’ hippocampi but taxi drivers had more volume in their posterior hippocampi.
- Correlational analysis - a positive correlation between time as a taxi driver correlated with the volume of the right posterior hippocampus
Conclusion: The results provide evidence for structural differences between the hippocampi of London taxi drivers and control participants, therefore suggesting that extensive practice with spatial navigation affects the hippocampus.
Evaluation:
- Which way round is this correlation? Does the brain structure influence job choice or does job choice influence your brain structure?
- Reliability: VBM and pixel-counting = scientific methods which should not be open to interpretation or experimenter bias. The analyst was ‘blind’ as to which group the brain scans came from, so they could not have interpreted them in a biased way (confirmation bias). So another analyst should obtain consistent results (test retest reliability). Ps did not actually have to do anything (except be scanned), which avoids participant biases, making it more likely that the findings would be consistent as it did not depend on measuring behaviours or thought processes.
- Validity: Being scanned in an MRI scanner is not ecologically valid, but it would not be possible for the Ps to respond to demand characteristics (internal validity).
- Reductionism: Focuses only on navigational experience, when other factors may have come into play as well, such as genes.
- Implications - your brain may enable you to perform a job more effectively due to specific neural connections that exist. Should you be scanned rather than interview?
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Lesson Materials
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