1. AS Psychology Research Methods
Experiments and Self-Reports

2. Experiments
An experiment looks for a relationship in which an independent variable (IV) is manipulated and is expected to be responsible for changes in the dependent variable (DV).
An independent variable is the variable which is manipulated by the experimenter that is presumed to effect the DV.
The dependent variable is assumed to be effected by the IV. Changes in the DV are presumed to have been caused by the IV.

3. Experiments Cont’d
An extraneous variable is a variable which either acts randomly, affecting the DV in all levels of the IV or systematically, such as one level of the IV (a confounding variable) so it can obscure the effect of the IV, making the results hard to interpret.
Psychologists try to control extraneous variables so as not to affect the IV or the DV.

4. Experimental Design
Independent Measures – using different participants for each condition of the experiment.
Strengths – no order effects, can use same stimulus materials, and less chance of demand characteristics.
Weaknesses – participant variables and more participants needed.

5. Design (Cont’d)
Repeated Measures – exposing the same participants to each condition.
Strengths – eliminates participant variables and fewer participants needed.
Weaknesses – ordered effects (boredom or practice), can’t use same stimulus materials, and easier to guess the aims of the experiment (demand characteristics).

6. Design (Cont’d)
Matched Pairs – matching each participant with someone who is similar to them, and placing them in different conditions.
Strengths – no order effects, can use same stimulus material, tries to control participant variables, and less chance of demand characteristics.
Weaknesses – difficult to match people, and more participants needed.

7. Experiment Types Laboratory – conducted in a lab setting.
Strengths – repeatable and thus reliable if similar results are produced, can use sophisticated measuring equipment, and more control over variables (could lead to knowing the cause/effect relationship).
Weaknesses – lack of ecological validity, artificial (lacks mundane realism), experimenter bias, and demand characteristics.

8. Types (Cont’d)
Field – an experiment in the real world where the IV is manipulated and as many variables are controlled.
Strengths – high in ecological validity, lacks demand characteristics, and experimenter effects reduced.
Weaknesses – less control (may be extraneous variables), difficult to replicate, lack of informed consent (ethics), sample bias (participants not randomly allocated), time consuming, and expensive.

9. Types (Cont’d)
Natural – an experiment by which the IV occurs naturally and the experimenter records effects on the DV.
Strengths – reduction of demand characteristics and the investigator doesn’t intervene.
Weaknesses – less control (the investigator doesn’t control the IV) and a cause and effect relationship is difficult to establish.

10. Ethics
Informed consent – the participant must be well aware of the research, risk, purpose of research, and withdrawal rights.
Right to withdraw – participants have the right to leave, participants do not have to provide a reason for their withdrawal, no negative consequences upon the choice of withdrawal, and right to remove their results from the study.

11. Ethics (Cont’d)
Confidentiality – participants must not be identified without consent, informed consent refers to privacy, and an explanation of the details of their development in a study such as a personal information cannot be revealed.
Deception – informed of the true purpose of the experiment, correction of any mistaken beliefs upon the participant, the research must provide an opportunity for the participants to examine the information, debriefing must occur after deception has occurred, and should refer to relevant assistance if there is any issues post experiment.

12. Ethics (Cont’d)
Debriefing – sometimes providing specific information about the study may influence participants and how they think, feel, and behave. This may influence the results therefore, secrecy or deception may be employed as long as: no harm is done to the participant and the participant is debriefed after the experiment.
Protection from harm – must ensure no physiological or psychological harm is done, guard the welfare of the participant, no experiment can causes distress, and rights are more important than the research.

13. Ethics (Cont’d)
Strengths – the knowledge gained may be valuable, so a small amount of harm may be justified. Being unethical can stimulate or help create a more realistic/ecologically valid situation.
Weaknesses – being unethical invades human rights. Participants may make a false assumption about the true nature of the study and behave in a way in which the experiment doesn't wish (demand characteristics).

14. Self-Reports
A self-report is a research method: a questionnaire or interview, which gathers data by asking participants to provide information about themselves.
A questionnaire uses written questions, which can be open (What are your views on…?) or closed (checkboxes).
An interview can either be structured (a set of questions pre-determined), unstructured (questions aren’t decided in advance) or semi-structured (Some questions are pre- prepared, however, the investigator is free to add more during the interview).

15. Self-Reports (Cont’d)
Strengths – participants are given the opportunity to express a range of feelings and explain their behavior. The data obtained may be "rich" and detailed, especially with open-ended questions.
Weaknesses – closed questions often don't give the participant the opportunity to say why they behaved or answered a question in a particular way. Participants may provide socially desirable responses, not give truthful answers or respond to demand characteristics.

16. Questionnaires
Strengths – gathers information from a large number of people efficiently, can use quantitative or qualitative analysis, quite easy to replicate, doesn’t require researcher to be present (reduces investigator effects), and people may be more willing to reveal personal information.
Weaknesses – low response rates (reduces validity), social desirability, people may misunderstand questions, not flexible (researcher cannot ask other questions that might arise), and only includes people who can read/write.

17. Interviews
Strengths – they tend to be more flexible as researchers can interact to clarify information, detailed qualitative information, unstructured format gives new insights, and sensitive issues can be explored.
Weaknesses – investigator bias, data can be misinterpreted, time-consuming, demand characteristics, and interviewee may be unable to convey their true thoughts.