Understanding how the brain can grow and change as a result of our environment and experiences is an exciting and important new field in psychology. Maguire’s study on this topic is already a classic.
Context
One of the most fascinating (relatively) recent discoveries is the idea of neuroplasticity: the brain’s amazing ability to grow and change as a result of different experiences. This is a new, diverse and exciting field in modern neuropsychology.
While Milner’s case study on HM (read more here) showed that a cognitive process (e.g. memory) can be altered by changes in our physiology (e.g. the removal of the hippocampus), Eleanor Maguire’s research shows that the reverse is also possible – how much we use specific cognitive processes can actually change the shape and structure of the brain. In particular, she investigated how extensive use of visuo-spatial memory interacts with the development of the hippocampus.
- Visuospatial memory: The ability to remember visual information, e.g. how to get to school from your house or what your bedroom looks like.
Maguire et al.’s original study (2000) showed a difference in hippocampal volumes between taxi drivers and a control group, but this 2006 study controlled for more confounding variables.
In a study in 2000 (read more here), Maguire showed that experienced male London taxi drivers had different structured hippocampi than a control group of non-taxi driving males. There was also a positive correlation between the number of years’ driving experience the taxi drivers had and how much their hippocampi volume (i.e. size) had changed. One issue with this study, however, was that there were a lot of possible confounding variables, so Maguire designed a new experiment and in 2006 she used MRI scans to compare the brains of taxi drivers and bus drivers.
Key Study: A comparison of hippocampal volumes in bus and taxi drivers in London (Maguire, 2006)
This quasi-experiment compared MRI scans of experienced London taxi drivers to London bus drivers. MRI scans allow researchers to see the shape and structure of the brain. The taxi drivers had all been through “the training”, which involves learning about 25,000 streets in London, thousands of landmarks and learning how to navigate through London without the use of satnavs or maps. In short, they are required to develop their visuo-spatial skills to an incredible degree.
The researchers wanted to ensure that occupation stress and driving experience were not confounding variables so this is why they chose bus drivers – it’s easy to find bus drivers who have many years’ driving experience and they also have to deal with customers, much like taxi drivers when they get on and off the bus, so their occupational stress levels would be comparable. There were 35 male participants in total (18 taxi and 17 bus drivers) and both groups were similar in age, driving experience, education level, and even handedness (i.e. if they were left or right handed). Both groups had MRI scans and they were also given memory tests. The memory tests included testing their ability to recognize London landmarks and their ability to recall faces and remember stories.
Results
The Brains:
The researchers examined the scan results to check for differences between the two groups. They found no significant differences anywhere in the brain except for in the hippocampi. In the taxi drivers, the posterior hippocampi were larger and the anterior hippocampi were smaller than those of the bus drivers.
The Cognition:
Not surprisingly, the taxi drivers were better at recognizing London landmarks. However, the bus drivers were slightly better at some of the other cognitive tests. Interestingly, the taxi drivers were worse at acquiring and remembering new visuo-spatial skills.
Conclusions
This study provides us with one example of neuroplasticity – because it was a tightly controlled quasi-experiment we are able to draw causal conclusions with some confidence that it was the experience of driving taxis that caused changes to the taxi drivers’ hippocampi. It also gives us an example of how and why MRIs are used in modern studies involving the brain and behaviour, as well as the benefits of using quasi-experimental research methods when we want to study the effects of an independent variable but we cannot randomly allocate participants to conditions (because they’re naturally occuring).
Trav’s Teacher Tip
- While this study is relevant for topics in the biological approach for IB Psychology, I think there are better studies with more relevant and applicable examples of neuroplasticity for students. For example, I like looking at the effects of stress, poverty and neglect on the developing brain.
Critical Thinking Considerations
- How does this study demonstrate neuroplasticity? (Application)
- How does this study demonstrate a bi-directional interaction between cognition (memory) and physiology (hippocampus)? (Analysis)
- What does this study show about the relationships between the brain and behaviour? (Application)
- What are the strengths and limitations of this study? (Evaluation)
- For example, could the generalizability of these results be questioned? This is a very specific group of people who have been studied and it was a small sample size. What might be unique about these participants that might affect the extent to which we could expect the same results with other groups of people?
References
Maguire, Eleanor A. Wollett, Katherine, and Spiers, Hugo J. “London Taxi Drivers and Bus Drivers: A Structural MRI and Neuropsychological Analysis. Hippocampus; 16; 1091-1101 (2006). Accessed from: https://www.ucl.ac.uk/spierslab/Maguire2006Hippocampu
Travis Dixon is an IB Psychology teacher, author, workshop leader, examiner and IA moderator.