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Exam 2- Research Methods Review.docx

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York University
PSYC 2030
Lisa Fiksenbaum

Chapter 5 Introduction to Experimental Research Woodworth took experiment and gave it the definition it has todayDefining feature of experimental method Woodworth called independent variable which affects the dependent variableExperimenter holds all conditions constant except for one factor which is his experimental factor independent variableObserved effect is depended variable is some characteristic of behavior or reported experience Correlational method measures two or more characteristics of the same individuals and computes correlation of these characteristicsHas no independent variable but treats all measured variables alike Essential Features of Experimental ResearchExperiment systematic research study in which investigator directly varies some factor hold all other factors constant observes results of variationFactor under control called independent variableFactors held constant referred to as extraneous variableBehaviours measured dependent variable Box 51 John Stuart Mill and the Rules of Inductive LogicJohn Stuart mill wrote A system of logic ratiocinative and Inductive Mill argued for creation of a science of psychology called it ethologyMethods that form logical basis methods of Agreement Difference Concomitant Variation called Joint MethodAgreement and Difference enable us to conclude with some outcome Y caused by some factor XAgreement states X is regularly followed by Y x is sufficient for Y to occurDifference states Y does not occur then X does not occur X is necessary for Y to occur if not X then not YExperimental group accomplishes mills method of agreement while control group does difference Establishing Independent VariablesX is Woodworths independent variable factor of interest to the experimenter sometimes called manipulated factors experimenter has complete control over itIndependent variable has minimum two levels experiment is comparison bw 2 conditionsExperiments take place in field called field experimentsField research any empirical research outside laboratory Varieties of Independent Variables Independent variables fall into three categories situational task and instructional Situational variables different features in environment participants might encounter helping behavior study situational variable would beof helpers on scene besides participantTask variables give groups of participants different kinds of problem to solveInstructional variables manipulated by asking different groups to perform a particular task in different ways Possible to combine several types of IV in single study Control GroupsExperimental group treatment is presentControl group treatment is withheldControl group Comparison group identical in all waysControl groups used only when its important to have comparison with a base level of performance Research Example 4 Experimental and Control GroupsNetherlands by Gerarts Bernstein Merckelbach Linders Raymaekers and Loftus 2008Researchers create false memory in students then examined effects of false memory on subsequent eating behaviourSubjects in experimental group less likely to choose egg salad than those in control group Controlling Extraneous VariablesSecond feature of experimental method is researcher tries to control extraneous variableAny variable not of interest to researcher but might influence behavior being studies if not controlled properlyConfound any uncontrolled extraneous variable that covaries w IV could provide alternative explanation of resultsResults could be due to effects of either confounding variable or independent variable or some combination of the twoVerbal learning experiment massed practice cramming the night before predicted to be inferior to distributed practice Confound 1 Total practice hours 2 retention interval Measuring Dependent VariablesThird part Dependent Variable those behaviors that are measured outcomes of experiments Key component operational definition for behaviors being measures as DV unless defined precisely replication impossibleTwo major problems w poorly chosen DV 1 Ceiling effect occurs when average scores for different groups in study so high that no difference can be determines happens when dependent measure so easy everyone get s high score 2 Floor effect All scores are extremely low because task is too difficult for everyoneManipulated Vs Subject VariablesSubject Variables already existing characteristics of individuals participating in study sex age class culture personality researcher cannot manipulate them Research Example 5 Using Subject Variables Research using subject variablesJi Peng and Nisbett 2000 difference bw those raised in Asian Cultures and those raised in Western CulturesRod and Frame test RFT used goal is making rod perfectly vertical regardless of frameResults female being more field dependent than malesThose from East Asian cultures were more field dependent than European AmericansStudies using independent variables that are subject variables are called ex post facto studies natural group studies quasi experimentsDrawing Conclusions when using subject variablesWith subject variables causal conclusions cannot be drawn reason has to do with amount of control held by experimenter in each caseUsing subject variables experimenter can vary some factor but cannot hold all else constantBox 52 Bobo Dolls and AggressionAlbert Bandura imitation of FilmMediated Aggressive Models Establishing Independent VariableThe major manipulated variable was type of experience preceded by opportunity for aggression4 levels including three experimental groups and one control groupReallife aggressions humanfilm aggression cartoonfilm aggression no aggressionNonmanipulated independent variable was sex Controlling extraneous variablesSeveral confounds avoided1 Size relationship bw person and doll approximately constant2 For all children approximately equal increase in their degree of emotional arousal Measuring dependent variablesAggressive responses categorize as imitative partially imitative or nonimitative Imitative aggressive behavior striking the doll with a malletPartially imitative sitting on doll but not hitting itNonimitative acting aggressively towards other objects in roomChildren in group 123 showed more aggression than control groups boys more aggressive than girls in allThe Validity of Experimental Research Psychological research valid if provides understanding about behavior it is supposed to provide 4 types of validity statistical conclusion validity construct validity external validity and internal validityStatistical Conclusion ValidityConcerns the extent to which researcher uses statistics properly and draws appropriate conclusions from statistical analysis SCV reduced if 1 Researchers do wrong analysis or violate assumptions required for performing particular analysis 2 Researchers might selectively report some analyses that came out as predicted but not report others 3 Reliability of measures usedConstruct Validity Refers to adequacy of operational definitions for both IV and DV in study
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