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1.3 Research in Psychology: Experimental Methods

1.3 Research in Psychology: Experimental Methods. Pgs. 25 - 29. The Use of Experiments in Psychology. GOAL: establish cause and effect relationship between two variables Experiment: Quantitative research (generates numerical data) Variables

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1.3 Research in Psychology: Experimental Methods

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  1. 1.3 Research in Psychology: Experimental Methods Pgs. 25 - 29

  2. The Use of Experiments in Psychology • GOAL: establish cause and effect relationship between two variables • Experiment: • Quantitative research (generates numerical data) • Variables • Independent Variable (IV): variable being manipulated or changed in the study • Dependent variable (DV): the variable that is being measured Variables must be Operationalized, i.e. they must be measurable.

  3. Apply your knowledge – pg 26 • Operationalize your variables by considering each of the following descriptions and deciding whether it is an example of aggression or not. • Two men fight over a parking space • A football player kicks the ball into a goal • Two girls give a boy the “silent treatment” on the playground • A man kicks the back of the car when it will not start • Three students have a heated debate about whether global warming is happening. • Know write a well worded definition of aggression.

  4. The Experiment • The Experimental Hypothesis predicts the relationships between the IV and the DV • Null Hypothesis: predicts that there will be no results or that the results will be due to chance. • The Control Group has no experimental actions applied to it. • WE CAN NEVER PROVE ANYTHING…..WE CAN ONLY DISPROVE. • Accept the null hypothesis • Refute the null hypothesis • Except experimental hypothesis if demonstrate effect due to IV manipulation.

  5. Be a Thinker pg 27 • Identify the IV and DV in each of the experimental hypotheses: • People are more likely to make a risky decision when they are in a group than when they are alone. • An increase in carbohydrates decreases ones ability to concentrate. • People will react more quickly to an auditory stimulus than a visual stimulus. • Lack of sleep will affect learning new word negatively. • Children who have watched a film with a model hitting a blow-up doll will exhibit more aggressive acts toward a blow-up doll than children who have not watched the film.

  6. Different Kinds of Experiments • Laboratory experiments • Field experiments • Natural experiments

  7. Laboratory experiments • Pros: • Easy to control • Easy to replicate • Cons • Artificial environment • What is the ecological value? • Would your result stand up outside of a lab setting?

  8. Field Experiment • Pros • Used in Social Psychology • Takes place in natural environments, but IV is still manipulated. • e.g. Piliavin and Rodin (1969) helping behavior in a New York Subway • Kitty Genevese1964 • The bystander effect • Cons • Cannot control all variables

  9. Natural Experiment • Natural experiment or quasi – the researchers have no control over the variables • Research on stoke patients • Cannot change gender • Children who have been separated from their parents due to war

  10. Points to consider with experiments • ConfoundingVariables: undesirable variables that influence the relationship between the IV and DV. • Artificiality – the situation is so unlikely that one has to wonder if there is any validity to the study

  11. Points to consider with experiments cont., • Three of the most common confounding variables: • Demand characteristics or Hawthorn Effect –participants behave in a manner that they think they should to meet the demands of the study. • To overcome – Single Blind control – participants do not know what the study is about. • Researcher Bias or observer bias- the researchers sees what he wants to see. • To overcome – Double Blind control – the participants & researcher do notknow who is in the control group vs. experimental group • Participant Variability – sample represents same characteristics • Overcome – random sampling

  12. Correlation studies • Not all experiments can be carried out, however, data can reveal relationships between two variables = Correlations • Correlation – as one variable changes the other variable changes. This does not mean there is a cause and effect. • Positive correlation: as X increases Y increases • Negative correlation: as X increases, Y decreases • Note – no IV is manipulated, thus there is not cause and effect.

  13. Advantages of Correlation Studies • They are simple and provide a numerical representations of the relationship that can be easily understood • They allow the study of a number of variables that cannot be manipulated experimentally.

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