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Experience Carefully Planned: Experimental Research Designs.

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Presentation on theme: "Experience Carefully Planned: Experimental Research Designs."— Presentation transcript:

1 Experience Carefully Planned: Experimental Research Designs

2  Laboratory experiments allow researchers to see how things turn out when one and only one thing is changed

3  Manipulation  Random assignment (vs matching)

4  Confound  When an additional variable (nuisance variable) exists that may influence the dependent variable and that varies systematically along with the independent variable.  Confounds threaten internal validity. It can be reduced through random assignment and by holding conditions constant.

5  Artifact  A variable that is held constant in a study but which influences the relation between the independent and dependent variables.  Artifacts threaten external validity. It can be reduced through random selection and maximizing experimental realism.

6  Noise-  Extraneous variable in an experiment that influences the dependent variable but that is evenly distributed across the experimental conditions.  Noise does not threaten validity, but it decreases the ability to detect an effect statistically. It can be reduced through the use of homogenous samples.

7  Person Confound  people who are high or low on this variable also happen to be high or low on some individual difference variable that is associated with the outcome variable of interest  Reduced or eliminated through random assignment

8  Procedural Confound  Researcher mistakenly allows a second variable to vary along with a manipulated variable  Eliminated by repeating the study while controlling for this variable

9  Operational Confound- when a measure designed to assess a specific construct inadvertently measures something else as well. It can be eliminated by refining the operational definition (measure).

10  Eliminate individual differences (person confounds)  Eliminate other kinds of confounds (procedural and operational confounds)  Pull researchers into the laboratory (controlled environment)

11  Allow researchers to observe the invisible (e.g. fMRI)  Provide information about interactions (through stats)  Minimize noise (reduced variability)

12  Problem: Artificiality  Solution: Two forms of realism (mundane and experimental)

13  Mundane Realism- the degree to which the physical setting in an experiment is similar to the real-world setting in which the experimenter’s independent and dependent variables are most likely to operate

14  Experimental Realism- the degree to which the subjective experiences of research participants are realistic or psychologically meaningful. Well-designed experiments can be high in experimental realism even when they bear little physical resemblance to the real world.

15  A recipe for experimental realism?  Manipulation checks throughout an experiment asking research participants about their experience  Deception

16  There is a perceived conflict between internal and external validity because confounds threaten internal validity and artifacts threaten external validity.

17  A highly controlled experimental design will eliminate confounds, but can also be considered an artifact. On the other hand, a loosely controlled experiment is often subject to many confounding variables.  Experiments that are high in either mundane realism or experimental realism tend to be high in both internal and external validity.

18  Experimental versus nonexperimental strategies  Laboratory versus field experiments

19  Setting the stage  Rehearsing and playing the part:  Be suave- Be honest  Be nice- Be a good liar  Be educated- Be attentive  Replicate as needed

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