Please enable JavaScript.
Coggle requires JavaScript to display documents.
Maguire et al - Evaluation - Coggle Diagram
Maguire et al - Evaluation
Tell a Story
Background
Hippocampal volumes are increased in small mammals/birds that show behaviour requiring spatial memory
Differences in structure of healthy human brains. E.g. between males and females, musicians and non-musicians
Method
Design: Quasi experiment, independent measures, matched participants design. IVs were whether or not the participant was a London taxi driver. DV was volume of hippocampi including their anterior, body, and posterior regions; measured by analysing MRI scans using VBM and pixel counting
Sample: 16 healthy, right-handed, male London taxi drivers. Mean age 44 years, mean time as taxi driver 14.3 years. Control did not drive taxis (50VBM, 16 pixel counting) matched for health, handedness, sex, mean age, and age range
Procedure: Scans of control group selected from structural MRI scan database at same unit where taxi drivers scanned MRIs analysed using VBM and pixel counting (analysed by one person experienced in technique and blind to whether scan was control group or not and VBM)
Results
Taxi drivers increased grey matter volume in right and left posterior hippocampi compared to controls
Controls increased grey matter volume in right and left anterior hippocampi
Positive correlation between length of time as taxi driver and right posterior hippocampal volume, but negative for anterior hippocampal volume
Conclusions
Regionally specific structural differences
Professional dependence on navigational skills in licensed London taxi drivers associated with relative redistribution of grey matter in hippocampus
Changes in arrangement of hippocampal grey matter acquired
Possibility of local plasticity in structure of normal human brain which allows to adapt in response to prolonged environmental stimuli
How does the study relate to the area
A modern counterpart to Blakemore and Cooper's study which again illustrates brain plasticity. This time, though, it illustrates it amongst adult humans (specifically London taxi drivers) in a different part of the brain (the hippocampi). It also uses different techniques (MRI scans) to investigate it. This study also explains brain plasticity, in that the organisation of the brain is altered by experiences
Research methods
One strength of a quasi experiment is that it uses naturally occurring independent variables. In the Maguire study, participants were either London taxi drivers or not London taxi drivers. This is a strength as it allows us to investigate independent variables that would be unethical to manipulate, in this case it would be unethical to make someone become a taxi driver
One weakness of a quasi experiment is that, because it uses naturally occurring variables, it cannot be manipulated. In Maguire's study, the requirements for participants were specific and naturally occurring. This is a weakness as it narrows down possible participants as they had to fit all of the following: healthy, right-handed, male, and a licensed London taxi driver
Research techniques
One strength of the matched pairs design is that it is easier to compare results as most characteristics of the participants are matched up with someone else, eliminating any chance of other factors affecting the results. In the Maguire study, the participants were matched up for health, handedness, sex, mean age and age range. This is a strength as it suggests the only variable that could affect the results is whether or not the participant is a taxi driver.
One weakness of that matched pairs design is that not all extraneous variables have been matched. For example, the area in which they live in. This could be a weakness as this could affect the results as it could become an extraneous variable
How does the Maguire study change our understanding of the key theme?
The key theme is brain plasticity. In the Blakemore and Cooper study, they came to the conclusion that visual experiences in the early life if kittens can modify their brains and have profound perceptual consequences. In the Maguire study, they investigated whether differences in brain structure is susceptible to plastic change in response to environmental stimulation. They investigated this by gathering 16 taxi drivers and 50 non-taxi drivers to compare their brain structure. Results form the brain scans showed that taxi drivers had increased grey matter volume in the right and left posteriori hippocampi whilst the controls had greater grey matter volume in the right and left anterior hippocampi. Correlations showed a significant positive correlation between the length of time as a taxi driver and the right posterior hippocampal volume, but a negative correlation for the anterior hippocampal volume. The Maguire study adds to the key theme as it shows that there are regionally specific structural differences and indicates a normal human brain which allows it to adapt in response to prolonged environmental stimuli
Core studies in their pairs
How the studies are similar
One similarity between the studies is that they are both useful. This means they can be used to add to our understanding of behaviour. Blakemore and Cooper showed that limiting the visual environment of kittens (vertical or horizontal only) affected the orientation of visual neurons hence the environment can impact the brain in kittens (plasticity). Similarly, Maguire showed a positive correlation between the length of time someone was a taxi driver and the density of grey matter in the right posterior hippocampi thus environment can also impact brain structure in humans as well
One similarity between the studies is that they both use an independent measures design. This means each group of participants only partake in one IV. Blakemore and Cooper had one group of kittens reared in a horizontal environment, whilst the other group were reared in a vertical environment. Similarly, Maguire had participants separated into whether or not they were a taxi driver
How the studies dffer
One difference between the studies is that Blakemore and Cooper uses a lab experiment whilst Maguire uses a quasi experiment. This means that Blakemore and Cooper took place in a controlled environment whilst Maguire uses naturally occurring variables as the IV cannot be manipulated. Blakemore and Cooper brought the kittens up in a completely dark room. After two weeks, they were put into a special cylinder with either vertical or horizontal lines. They were given time in a room with tables and chairs after 5 months to be observed. However, Maguire's IV was whether or not the participant was a taxi driver, which cannot be manipulated as it is a naturally occurring variable