1. Unit 1: History of Psychology and Research Methods
1.5 Experimental Research & Ethical Issues

2. Experiments Experimental Method:
method where a researcher changes one variable and then observes the effect on another variable
Participants receive a treatment; researches observe how the treatment affects behavior
Observational vs. Experimental:
Observations describe and make predictions about behavior but don’t describe the reasons behind the behavior
Experiments focus on cause and effect

3. Variables Independent variable - the “cause” variable
the factor in an experiment that researchers can change/manipulate to see the effect it causes
Dependent variable
- the “effect” variable
- the factor that changes in response to the independent variable

4. Groups
Experimental Group: participants who get the treatment Control Group: participants who don’t get the treatment All other conditions are as similar as possible

5. Try it out:
Type of reading class
Reading skill
Amount of sleep
Score on memory test
Amount of walking
Lung capacity
Using or not using a cellphone
Performance on simulated driving test
The independent variable is:
The dependent variable is:
1. Children’s reading skill is measured after taking either a special reading class or a standard reading class
2. College students’ memory for German vocabulary words is tested after a normal nights sleep or a night of no sleep.
3. Experiment title: “The effect of a daily walking program on elderly people’s lung capacity.”
4. People’s ability to avoid ‘accidents” in a driving simulator is tested before, during, and after talking on a cell phone.

6. Assignment & Bias Random Assignment:
Assign participants to experimental or control group by complete chance
Reduces experimenter bias
Experiment Bias:
Researcher’s expectations can skew results of the study
Experimenter might accidently alter participant’s behavior

7. Assignment & Bias
To reduce bias – Single-Blind Studies: participants don’t know whether they are receiving treatment or not Double-Blind Studies: participants AND researchers don’t know who is receiving treatment Placebo: participants THINK they are getting treatment, but it doesn’t actually do anything - Placebo Effect: people expectations influence their experience (if they take a placebo drug meant to help headaches, they might report feeling better after an hour)

8. Ethical Issues Ethics: standards for proper and responsible behavior
Common ethical concerns:
Informed consent – people know what they are signing up for OR they are debriefed after the experiment if deception is involved
Anonymity/confidentiality – names/data kept anonymous or confidential to protect people’s privacy
No long-term harm – no lasting physical or psychological harm should result (though short-term discomfort is okay)