Lecture Slides
Video Lecture (from 2019)
Concepts
Classical Experimental design
Independent variable
Dependent variable
Random assignment
Pretest
Posttest
Experimental group
Control group
Key Concepts:
Double-blind experiment
Confederates
Placebo
Deception
Debrief
Types of experiments:
Classical experimental design
True experiment
Quasi-experiment
One-shot case study
Natural experiment
Field experiment
Validity:
Internal validity
External validity
Variable:
Conceptual
Operational
Double-Blind Experiment
When neither:
- The person carrying out the experiment (research assistant)
- The person in the experiment (participant)
knows the true purpose of the study.
Why is it important to run double-blind experiments?
Avoids conscious or unconscious bias.
Confederates
People who work for the researcher and deceive the participants by making them believe the confederate is just another participant or a bystander.
E.g. Student in Milgram study
Placebo
A treatment, normally given to the control group, that is designed to have no effect. It gives the participant the impression they have had a treatment when they have not.
E.g. A sugar pill in a medical study of anti-depressants.
Deception
An act of hiding some important information, or providing misleading information, to the participant.
It is a form of harm. It harms faith in other humans.
It is only justifiable if:
- There is no alternative
- Uses minimum necessary deception
- Benefits outweigh any risks
- Participants can withdraw information after debrief
E.g. Milgram’s lies to teacher about helping with a study of learning and punishment.
Debrief
A structured discussion after an experiment - normally after an experiment that involves some form of deception.
Discussion is between the experimenter (or their assistant) and the participant. The participant is explained true nature of study. Generally this also involves and opportunity to withdraw, an attempt by researcher to understand how participant understood the study, and also opportunity for participant to ask questions.