国外心理学研究方法17expdesign3ppt课件

ExperimentBasics Designs Psych231 ResearchMethodsinPsychology Experimentaldesigns Sofarwe vecoveredalotoftheaboutdetailsexperimentsgenerallyNowlet sconsidersomespecificexperimentaldesigns Somebad butcommon designsSomegooddesigns1Factor twolevels1Factor multi levelsFactorial morethan1factor Between withinfactors Example Whatistheeffectofpresentingwordsincoloronmemoryforthosewords Twodifferentdesignstoexaminethisquestion participants Coloredwords BWwords Test 2 levelsEachoftheparticipantsisinonlyoneleveloftheIV Between GroupsFactor ClockChairCab ClockChairCab 2 levels AlloftheparticipantsareinbothlevelsoftheIV ClockChairCab ClockChairCab Sometimescalled repeatedmeasures design Within GroupsFactor Betweenvs WithinSubjectsDesigns Within subjectsdesignsAllparticipantsparticipateinalloftheconditionsoftheexperiment Between subjectsdesignsEachparticipantparticipatesinoneandonlyoneconditionoftheexperiment Within subjectsdesignsAllparticipantsparticipateinalloftheconditionsoftheexperiment Between subjectsdesignsEachparticipantparticipatesinoneandonlyoneconditionoftheexperiment Betweenvs WithinSubjectsDesigns Betweensubjectsdesigns Advantages Independenceofgroups levelsoftheIV HardertoguesswhattheexperimentisaboutwithoutexperiencingtheotherlevelsofIVExposuretodifferentlevelsoftheindependentvariable s cannot contaminate thedependentvariableSometimesthisisa must becauseyoucan treversetheeffectsofpriorexposuretootherlevelsoftheIVNoordereffectstoworryaboutCounterbalancingisnotrequired Betweensubjectsdesigns DisadvantagesIndividualdifferencesbetweenthepeopleinthegroupsExcessivevariabilityNon Equivalentgroups Individualdifferences Thegroupsarecomposedofdifferentindividuals Individualdifferences Thegroupsarecomposedofdifferentindividuals Individualdifferences Thegroupsarecomposedofdifferentindividuals DealingwithIndividualDifferences StriveforEquivalentgroupsCreatedequally usethesameprocesstocreatebothgroupsTreatedequally keeptheexperienceassimilaraspossibleforthetwogroupsComposedofequivalentindividualsRandomassignmenttogroups eliminatebiasMatchinggroups matcheachindividualsinonegrouptoanindividualintheothergrouponrelevantcharacteristics Matchinggroups GroupA GroupB MatchedgroupsTryingtocreateequivalentgroupsAlsotryingtoreducesomeoftheoverallvariabilityEliminatingvariabilityfromthevariablesthatyoumatchedpeopleon RedShort21yrs Bluetall23yrs Greenaverage22yrs Browntall22yrs ColorHeightAge Within subjectsdesignsAllparticipantsparticipateinalloftheconditionsoftheexperiment Between subjectsdesignsEachparticipantparticipatesinoneandonlyoneconditionoftheexperiment Betweenvs WithinSubjectsDesigns Withinsubjectsdesigns Advantages Don thavetoworryaboutindividualdifferencesSamepeopleinalltheconditionsVariabilitybetweenconditionsissmaller statisticaladvantage Fewerparticipantsarerequired Withinsubjectsdesigns DisadvantagesRangeeffectsOrdereffects Carry overeffectsProgressiveerrorCounterbalancingisprobablynecessarytoaddresstheseordereffects Withinsubjectsdesigns Rangeeffects contexteffects cancauseaproblemTherangeofvaluesforyourlevelsmayimpactperformance typicallybestperformanceinmiddleofrange Sincealltheparticipantsgetthefullrangeofpossiblevalues theymay adapt theirperformance theDV tothisrange Ordereffects Carry overeffectsTransferbetweenconditionsispossibleEffectsmaypersistfromoneconditionintoanothere g Alcoholvsnoalcoholexperimentontheeffectsonhand eyecoordination Hardtoknowhowlongtheeffectsofalcoholmaypersist Howlongdowewaitfortheeffectstowearoff Ordereffects ProgressiveerrorPracticeeffects improvementduetorepeatedpracticeFatigueeffects performancedeterioratesasparticipantsgetbored tired distracted Dealingwithordereffects CounterbalancingisprobablynecessaryThisisusedtocontrolfor ordereffects Ideally useeverypossibleorder n e g AB 2 2orders ABC 3 6orders ABCD 4 24orders etc AllcounterbalancingassumesSymmetricalTransferTheassumptionthatABandBAhavereverseeffectsandthuscanceloutinacounterbalanceddesign Counterbalancing SimplecaseTwoconditionsA BTwocounterbalancedorders ABBA Counterbalancing OftenitisnotpracticaltouseeverypossibleorderingPartialcounterbalancingLatinsquaredesigns aformofpartialcounterbalancing sothateachgroupoftrialsoccurineachpositionanequalnumberoftimes Partialcounterbalancing Example considerfourconditionsRecall ABCD 4 24possibleorders1 UnbalancedLatinsquare eachconditionappearsineachposition 4orders Partialcounterbalancing 2 BalancedLatinsquare eachconditionappearsbeforeandafterallothers 8orders Example considerfourconditionsRecall ABCD 4 24possibleorders Mixedfactorialdesigns MixedfactorialdesignsTreatsomefactorsaswithin subjects participantsgetalllevelsofthatfactor andothersasbetween subjects eachlevelofthisfactorgetsadifferentgroupofparticipants Thisonlyworkswithfactorial multi factor designs