Paper 2 - Maguire et al On Taxi Drivers

Question 1

What is the background of this study

Answer 1

• The hippocampus is a small component of the brain. There is one hippocampus on each side of the brain - one in each hemisphere.
• Each is located in the the temperal lobe on the sides of the brain.
• Many birds and small animals have a need for spatial memory, e.g. find food. Reseaech has shown that the hippocampus is central to spatial memory, e.g. animals with batter spatial memoy have a bigger hippocampus.
• This study wanted to furthrt research of the hippocampus and spatial mempry within humans

Question 2

What is the aim of this study

Answer 2

• investigate the role of the hippocampus in spatial memory and navigation.
• More sepcifically to see if the brain is capable of changing in response so envronmental stimulation.
• To identify the precise role of the hippocampus in humans.
• To demonstrate the structural changes in the human brain in response to behaviour requiring spatial memory

Question 3

what is the design of this study

Answer 3

• quasi experiment - the IV varied naturally
• matched pairs design.

Question 4

what is the IV

Answer 4

whether a participant was a taxi driver or not

Question 5

what is the DV

Answer 5

the volume of each hippocampus measured in 6 areas.

Question 6

what is the sample

Answer 6

• self selected sampling - 16 right handed male taxi drivers who had passed their test to qualify as a taxi driver in London. This requires a detailed knowledge of London streets.
• The mean age was 44 years old.
• Mean training time was 2 years.
• All had healthy medical and neurological profiles.
• opportunity sampling - The control group was men who did not drive taxis. They were matched by health, age, gender and handedness. They were selected from a pool of 50 men whose records were in a MRI scan data base

Question 7

what are the materials of this study

Answer 7

• MRI scanner.
• uses magnets to detect the structure of the brain.

Question 8

what is the procedure for image analysis method 1 - VBM

Answer 8

Voxel based morphometry.
* This technique measures the volume of specific brain areas by comparing the brain to a template. The template was constructed using 50 healthy male brains and working out an average.
* VBM identifies differences in the density of grey matter in a person’s brain.
* VBM is an automatic procedure that uses statistical parametric mapping.

Question 9

what is the procedure of image analysis method 2 - pixel counting

Answer 9

• MRI scans were made of the brain by cutting 26 slices that were 1.5 mm thick. Each slice lay next to the previous one and included all areas of the hippocampi. Each slice presented a 2 dimentional picture.
• The pictures were analysed by one perspn who counted the pixels in each slice.
• The person doing the counting was blind to whether a pps was a taxi driver or not and was blind to the VBM results.
• A measure of totsl hippocampal volume was produced by adding the number of pixels in all slices and multiplying by 1.5.

Question 10

what were the reults from VBM

Answer 10

• there was significantly more grey matter in both hippocampi of taxi drivers compared to the control group
• The difference was only in the prosterior portion of the LH and RH.
• The controls had more grey matter in the anterior LH and RH.
• No differences anywhere else.

Question 11

What were the results of pixel counting

Answer 11

• Anterior LH and RH had a greater volume in the controls than in taxi drivers. P<0.05
• Prosterior LH and RH had a greater volume in the taxi drivers than in the controls. P<0.05
• Total hippocampi volume did not differ significantly between the groups

Question 12

what are the result for chnages in navigational experience

Answer 12

• there was a positive correlation between time spent taxi driving and volume of the prosterior RH.
• There was a negative correlation between time and the volume of the anterior RH and LH.

Question 13

what are the conclusions from this study

Answer 13

• the results suport the relationship between the hippocampus and navigational skills.
• The difference between the experimental and control groups suggests that the brain does change in response to experience, demonstrating brain plasticity.
• The correlation between experience in taxi drivers confirms the role of nurture in the development of the biological system.

Question 14

evaluate the method of this study

Answer 14

• strengths - quasi experiment allows for the study of a naturally occurring Iv. Matched pairs design controls participants variables (health, age, gender)
• Weaknesses - quasi means no control over the allocation of pps to the conditions. Even though there matched pairs, taxi drivers may differ in other things like IQ.

Question 15

evaluate the ethics of the study

Answer 15

• strengths - informed consent as the condition of an MRI scan allows for knowledge that your being studied.
• weaknesses - experience of the MRI scanner may have been harmful, anxiety and stress

Question 16

evaluate reliability of the study

Answer 16

• strengths - MRI scanner is a standardised technique conducted in a highly controlled environment. Voxel ad pixel counting is easy to repeat.
• Weaknesses - only one counter, low inter rater reliability.

Question 17

evaluate validity

Answer 17

• strengths- voxel and pixel counter was blind to the aim this reduces researcher bias which means high internal validity.
• weaknesses - MRI scanner found brain acitivty in a dead salmon which questions validity of MRI scanner results.

Question 18

evaluate the sample and ethnocentrism

Answer 18

• strengths - matched pairs design controls variables of health age and gender which allows for valid comparisons. self selcted sampling obtains willing pps who wont drop out.
• weaknesses - females were not used and pps were only british, this lowers population validity and means the study is ethnocrentric. Only right handed drivers were used which decreases representitiveness and population validity.

Question 19

evaluate the data

Answer 19

• strengths - quantitative data is objective and easy to analyse and draw statistical conclusions from for comparison.
• weaknessesc - there are no detailed explanations of why these results occur.

Question 20

what are the debates and perspectives of this study

Answer 20

• behaviourist - learning and environmental chnages can affect the brain structure and function
• nature and nurture - people are genetically predisposed to having a more plastic brain, however, the experience of navigating london’s roads changes the innate hippocampus volume.

Question 21

how is this study useful

Answer 21

it shows that it is possible to incresae the volume of grey matter through repeated use.
brain damage.