Longitudinal and cross-section studies, and brain scans

Question 1

Longitudinal study - definition

Answer 1

A study conducted over a long period of time.
Often a form of repeated measures design in which participants are assessed on two or more occasions as they get older.
Some longitudinal research is not experimental, people may simply be observed for a number of years.

Question 2

Longitudinal - advantage

Answer 2

Participant variables are controlled.
This is because longitudinal studies often use a repeated measures design.

Question 3

Longitudinal study - disadvantage

Answer 3

Attrition is a problem.
Some of the participants inevitably drop out over the course of a study.
This leaves a biased sample.
Participants are likely to become aware of the research aims.

Question 4

Cross-sectional study - definition

Answer 4

One group of participants representing one section of society are compared with participants from another group.
Example:
Young people compared with old people.

Question 5

Cross-sectional study - advantage

Answer 5

Quick.
Can be conducted in less than a year.

Question 6

Cross-sectional study - disadvantages

Answer 6

The groups of participants may differ in more ways than the behaviour being researched.
Cohort effects occur.
This is because a group of people who are all the same age share certain experiences.

Question 7

Brain scans - definition

Answer 7

A technique used to investigate the functioning of the brain by taking images of the living brain.

Question 8

CAT scans - key points

Answer 8

Involves taking a series of x-rays and combining them to form a comprehensive two-or-three dimensional picture of the area being scanned.
Usually a dye is injected into the patient as a contrast material and then they are placed in the cylindrical CAT scan machine.

Question 9

CAT scans - name of study

Answer 9

Johnstone et al

Question 10

CAT scans - Johnstone et al

Answer 10

Used CAT scans to show that the brains of people with schizophrenia were different to normal brains.
The fluid-filled spaces in the brain (ventricles) were much larger.

Question 11

CAT scans - advantages

Answer 11

Useful for revealing abnormal structures in the brain such as tumours, or structural damage.
The quality of the images is much higher than that of x-rays.

Question 12

CAT scans - disadvantage

Answer 12

Require more radiation than traditional x-rays.
The more detailed and complex the CAT scan is, the more radiation exposure the patient receives.
CAT scans only provide structural information.

Question 13

MRI scans - key points

Answer 13

Involves the use of a magnetic field that causes the atoms of the brain to change their alignment when the magnet is on and emits various radio signals when the magnet is turned off.
A detector reads the signals and uses them to map the structure of the brain.

Question 14

MRI scans - name of study

Answer 14

Maguire et al

Question 15

MRI scans - Maguire et al

Answer 15

Used MRI scans to demonstrate the taxi drivers had larger hippocampi than non-taxi drivers, supporting the view that this area of the brain is important in spatial memories.

Question 16

Functional MRI (fMRI) - definition

Answer 16

Provides both anatomical and functional information by taking repeated images of the brain in action.

Question 17

MRI scans - advantages

Answer 17

Gives a more detailed image of the soft tissue in the brain than CAT scans.
This is because it involves passing an extremely strong magnetic field through the patient rather than using x-rays.
Best suited for cases when a patient is to undergo the examination several times successively in the short term.
This is because, unlike CAT scans, it doesn’t expose the patient to the hazards of radiation.

Question 18

MRI scans - disadvantages

Answer 18

Take a long time.
Can be uncomfortable for patients.

Question 19

PET scans - key points

Answer 19

Scan involves administering slightly radioactive glucose to the patient.
The most active areas of the brain use glucose, and radiation detectors can “see” the radioactive areas, so building up a picture of activity in the brain.
Scans take between 10-40 minutes to complete and are painless.

Question 20

PET scans - name of study

Answer 20

Raine et al

Question 21

PET scans - Raine et al

Answer 21

Used PET scans to compare brain activity in murderers and normal individuals.
Found differences in areas of the brain such as the prefrontal cortex and the amygdala, regions previously associated with aggressive behaviour.

Question 22

PET scans - advantages

Answer 22

Reveal chemical information that is not available with other imaging techniques.
Means that they can distinguish between benign and malignant tumours.
Show the brain in action.
This is useful for psychological research.

Question 23

PET scans - disadvantages

Answer 23

Costly.
Not easily available for research.
The patient has to be injected with a radioactive substance.
This technique can only be used a few times.
Less precise than MRI scans.