longitudinal and cross sectional studies and brain scans

Question 1

What is a longitudinal study

Answer 1

Research conducted over a long period of time in order to observe long term effects e.g. difference between people of different ages

Question 2

What are case studies

Answer 2

Often longitudinal e.g. John Bowlby’s study. Essentially a series of case studies conducted over many years. Study how people change as they get older

Question 3

What is a cross sectional study

Answer 3

Compare different groups e.g. One group of participants of a young age are compared to another older group at the same point in time.

Question 4

Advantages of longitudinal studies

Answer 4

Control for participant variables: often uses repeated measures design (same person tested on a number of occasions) so all other variables controlled

Question 5

Advantages of cross sectional studies

Answer 5

Have the advantage of being relatively quick. Can be conducted in less than a year

Question 6

Disadvantages of longitudinal studies

Answer 6

• Attrition is a problem: some participants drop out over the course of the study. And the difficulty is that the ones who drop out more likely to have similar traits which leaves biased sample.
• Likely to become aware of research aims
• Difficult to finance

Question 7

Disadvantages on a cross sectional study

Answer 7

• Participants may differ in more ways than the researched behaviour. E.g. money in different professions.
• Cohort effects occur because a group of people who are all the same age share certain experiences.
• IQ’s of young seeming higher may be due to things that happened in the old person’s childhood, not due to IQ declining with age.

Question 8

EEG scan

Answer 8

First method. Electrodes placed on scalp and electrical activity in different regions of the brain recorded. E.g. sleep research because as people sleep, their brain waves slow.

Question 9

CAT scans

Answer 9

Taking a series of xrays and combining them to form a comprehensive 2-3D picture of the area. Dye injected into patient as contrast material. E.g Johnstone et al used CST to show brains of people with schizophrenia

Question 10

MRI scans

Answer 10

Use of magnetic field that causes atoms of the brain to change their alignment when the magnet is on and emit various radio signals when magnet is on or off. Detector reads the signals and uses them to map the structure of the brain. Functional MRI provides both anatomical and functional information by taking repeated images of the brain in action

Question 11

PET scans

Answer 11

Administer radioactive glucose to patient. Most active areas of the brain use glucose and radiation detectors can see the radioactive areas. E.g. Raine et al compared brain activity in murderers and normal individuals.

Question 12

Advantage of CAT scans

Answer 12

Revealing abnormal structures in the brain like tumours. Quality of images higher than other xrays

Question 13

Disadvantages of CAT scans

Answer 13

Require more radiation than traditional xrays. More detailed and complex the CAT scan is, the more radiation exposure the patient receives

Question 14

Advantage of MRI scans

Answer 14

More detailed image of the soft tissue in the brain than CAT do. Suited for cases when patient is to undergo the examination several times successively in short term because doesn’t expose to radiation

Question 15

Disadvantage of MRI scans

Answer 15

Take a long time and can be uncomfortable

Question 16

Advantage of PET scans

Answer 16

Reveal chemical information that isn’t available with other scans. Distinguish between benign and malignant tumours, and show the brain in action which is useful for psychological research

Question 17

Disadvantage of PET scans

Answer 17

Extremely costly technique and not easily available for research. Has to be injected with radioactive substance so can only be used a few times. Less precise than MRI scans