Dealing with Participants
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Dealing with Participants
OK, so you've thought up this brilliant psychological experiment and designed it perfectly.
But who are you going to try it out on?
Sampling techniques are very important. Several different types of sampling are used according to the type of study and the subjects you want to target.
Random sampling: Everyone in the entire target population has an equal chance of being selected.
Opportunity sampling: Uses people from target population available at the time.
Systematic sampling: Chooses subjects in a systematic way. For example, every 10th person from a list or register.
Self-selected sample: Participants volunteer. For example, by answering an advert.
Stratified sampling: Divides target population into groups, people in sample from each group in same proportions as population. So you would have a higher number of people between the ages of 20-30 than 70-80.
This does not mean becoming emotionally involved and going out with participants!
What it does mean is ways in which either the researcher or the participants can influence the results this is known as "causing bias".
Researcher effects: Researcher can affect the behaviour of the participants, thus affecting the results of the study.
The researcher might unwittingly communicate his expectations to the participants. This could happen through only small changes in body language or tone of voice.
Or it can be in the interpretation of data, a researcher may read into things more of what he or she would like to find!
An attractive researcher might affect participant responses. For example, male researchers smile at female participants more than they do at male ones!
Even rats learned mazes faster when expected to! (Rosenthal, 1966)
Just the presence of the researcher can affect participant behaviour, more so if the researcher is filming people.
Demand characteristics: Participants might read things into the situation and start changing their behaviour they respond to the perceived demands of the study.
Participants may worry about being in a psychological study and want to appear 'normal', this may change their behaviour.
Participants may try to guess what the investigation is about then behave in the way they think the investigator wants them to.
On the other hand, they may deliberately try to behave in an unexpected way. Unofficially known as the "f*** you effect").
Participants might just try to 'look good' (social desirability) and behave out of character or not tell the truth. This can be a problem for questionnaires on sensitive issues.
There are several things a researcher can do:
Disguise the purpose of the investigation: There is some deception in many psychological studies to stop participants guessing the aims and changing their behaviour. Participants in Milgram's obedience studies thought it was a study on effects of punishment on learning and memory.
Single-blind design: Participants do not know which condition (experimental or control) they are in. For example, the use of placebos in trials of drug treatments.
Double-blind design: Neither the participants nor the experimenter know which condition people are being treated to. For example, a research assistant giving out drugs and measuring their effects does not know who has the placebo and who has the drug.
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