1. Lecture 3: Critical Thinking
Honours Seminar
Lecture 3: Critical Thinking

2. Critical thinking
Tries to function independently of preconceived notions of how the world functions
Focuses on the simplest explanation of events
Thinks of ways in which a conclusion may be at fault
Tries to think of ways to strengthen research designs to isolate an dependent variable

3. Every study has flaws. But every study also shows something.
But studies do not always show what the authors think they show. Knowing the difference is the basis of critical thinking.

4. Trends in research designs
Observational research
Participant observation
Correlational research
Quasi-experimental research
Experimental research
Blind, Double-Blind
Example: You wish to show that caffeine causes accelerated motor behaviour in students

5. Correlational research designs
Direction of causality
Example: A soccer ball is kicked. It goes up a certain height and is in the air a certain length of time. Does the height cause the time, or does the time cause the height?
A causes B
B causes A
C causes A and B

6. The importance of experiments
Random assignment should equate your groups on individual differences
Self selection to groups means that non-random influences could account for the differences between the groups
There are other problems with experiments:
Diffusion of your treatment
“Hypothesis guessing”
Attrition can result in loss of randomisation

7. Construct validity of measures
What are you measuring?
Are you sure you are measuring what you are measuring?
Example:
Obese and non-obese people are in a waiting room
Shelled and non-shelled peanuts are available
Obese people eat more non-shelled peanuts
How do you interpret these results?
Can you offer an alternative explanation for these results

8. External validity
Results may not generalise to other samples or populations
Why? What non-random effects exist in your sample that may differ from others?
Example: A study of reading conducted in Nova Scotia. Will it generalise to other provinces? Why or why not?
Psychology students are recruited into a study to show that family disruption is related to well-being at university.

9. Translate the research questions into an experimental research design
Observational research
Participant observation
Correlational research
Quasi-experimental research
Experimental research
Blind, Double-Blind