Psych 325 1st Edition Lecture 21 Tuesday, April 21Chapter 7--Experimental Research DesignsRecap part 1: basic featuresPart 2: strengths of experimental designsBrief Exam 3 Review Session -Part II: The Strengths of Experiments-Strengths: Eliminates individual differencesoDifferences between groups can't explain differencesoRandom assignment to condition accomplishes this-Strengths: Eliminates Other ConfoundsoLaboratory environment helps eliminate confoundsoIt's not perfect, though!oProcedural confound-The procedure manipulates more than one thing-Threatens internal validityoOperational confound-The IV isn't what you think it is-You'll have trouble interpreting any significant findings-Not internal validity problem-Isen & Levin (1972, 1987; p. 182 &185): Eliminating other kinds of confounds-Strengths: Pulls Researchers Into the LaboLabs have many disadvantages over field experimentsoComplete control over the environment in laboEasier to eliminate confoundsoCan measure things that are "invisible" using advanced technology or questionnairesoEliminates natural confounds that occur in the field-Strengths: Can Observe the InvisibleoPhysiological assessments of things like stress and attitudesoFunctional MRI imaging allows us to see brain activityoImplicit association measures get at hidden prejudiceoCan monitor many different, subtle aspects of behavior-Strengths: can study interaction effectsoMay need to study the effect of two variables togetheroExperiments allow you to control, isolate, and combine variablesoInteraction effect-Effect of one variable differs depending on levels of another-Tells you when or under what conditions causation occurs-Can identify boundary conditionsWhen a theory isn't trueThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Qualification approach-Strengths: minimize noiseoNoise: "extra" variables that affect all conditions equally-Subject variables-Random eventsoNot a confound-Increases range of DV-Makes it harder to find an effectoExperiments limit noise-Fewer extraneous causes-Similarity across conditionsoUsing similar people limits noise, but also limits generalizability-What about artificiality?oLabs eliminate noise and confounds, but at a costoIs the unusual environments of the lab an artifact that limits the generalizability of findings?-Observed effects may only occur in laboratories-May not apply to the real worldoHowever, we don't want to emulate reality, we want to see under the surface of reality-Two forms of realismoMundane realism-Degree to which your setting looks like the real world-Doesn't guarantee usefulnessoExperimental realism-Are you studying a genuine psychological response-Subjects need to be engaged for the study to matter at all-Without it, mundane realism doesn't matteroWell done studies will almost always be useful-A recipe for experimental realismoThere are no explicit rules-Every situation is different-Use trial and erroroRead prior literatureoBuild participant interest-Use a good cover story-Perhaps use deceptionoGuarantee construct validity-Use manipulation checks-Pilot test your