Honours Seminar Lecture 3: Critical Thinking

What is the basis for the title of this movie?

What caused the shootings at Columbine High School? Marilyn Manson Music? Marilyn Manson Music? Bowling?Violent History? Bowling?Violent History? Accessibility of Guns? Accessibility of Guns?

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

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.

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

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? 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 A causes B B causes A B causes A C causes A and B C causes A and B

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

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

External validity Results may not generalise to other samples or populations Results may not generalise to other samples or populations Why? What non-random effects exist in your sample that may differ from others? 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? 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. Psychology students are recruited into a study to show that family disruption is related to well-being at university.

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