Experimental Psychology Notes Week 3
Experimental Psychology Notes Week 3 PSYC 266 - 04
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This 3 page Class Notes was uploaded by Elizabeth Schnarr on Friday September 9, 2016. The Class Notes belongs to PSYC 266 - 04 at Truman State University taught by Ashley Ramsey in Fall 2016. Since its upload, it has received 4 views. For similar materials see Experimental Psychology in Psychology at Truman State University.
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Date Created: 09/09/16
Week 3: 9/59/11 Experimental Psychology Operational Definitions, Reliability, and Validity Operational Definitions ● An operational definition specifies the exact meaning of a variable in an experiment ● Experimental operational definition specifies the exact procedure for creating values of the .V ● Measured operational definition specifies the exact procedure for measuring the D.V Reliability ● Reliability refers to the consistency of experimental operational definitions and measured operational definitions ● Interrater reliability: the degree to which observers agree in their measurement of the behavior (Ex: how much graders agree on scoring an essay) ● Testretest reliability: the degree to which a person's scores are consistent across two or more administrations of a measurement procedure (Ex: Highly correlated scores on the Wechsler Adult Intelligence ScaleRevised when it is administered twice, 2 weeks apart) ● Interitem Reliability: measures the degree to which different parts of an instrument that are designed to measure the same variable achieve consistent results (looking at the same thing) Validity ● Means if what’s intended to be measured is what’s being measured ● Face Validity: the degree to which the validity of a manipulation or measurement technique is selfevident (obvious choice) ● Content Validity: how accurately a measurement procedure samples the content of the dependent variable (Ex: an exam over chapters 14 that only contains questions about chapter 2 has poor content validity) ● Construct Validity: how accurately an operational definition represents a phenomenon that is not directly measurable (Ex: memory tasks) ● Predictive Validity: how accurately a measurement procedure predicts future performance Week 3: 9/59/11 ● Concurrent Validity: degree to which scores on the measuring instrument correlate with another known standard for measuring the variable being studied (Ex: Compare tests results on a measure of anxiety to evaluations by a clinician) ● Internal Validity: degree to which changes in the dependent variable across treatment conditions were due to the I.V ● External Validity: degree to which research findings can be generalized to other settings and individuals Experimental Psychology Controlling Extraneous Variables Physical Variables ● Physical variables are aspects of the testing situation that need to be controlled ● Elimination completely removes extraneous physical variables from the experimental situation (Ex: soundproofing a room) ● Constancy of conditions controls extraneous physical variables by keeping all aspects of the treatment conditions identical, except for the independent variable (Ex: testing all subjects at the same time of day) ● Balancing controls extraneous physical variables by equally distributing their effects across treatment conditions (Ex: running half the subjects in the morning, and the other half in the afternoon) ● Order: 1. Eliminate extraneous variables whenever possible 2. Keep conditions constant where elimination is not possible 3. Balance the effects of extraneous variables when constancy of conditions is not possible Social Variables ● Social variables are aspects of the relationships between subjects and experimenters that can influence experimental results ● Demand characteristics are cues within the experimental situation that demand or elicit specific participant responses (Ex: students cue professors that time is up by packing up backpacks) Week 3: 9/59/11 ● Demand characteristics can confound internal validity if they vary across experimental conditions ● Subjects may act to confirm what they think is the experimental hypothesis ● In a singleblind experiment, subjects are not told their treatment condition ● Placebo effect is when a subject receives an inert treatment and improves because of positive expectancies ● Cover story is a false plausible explanation of the experimental procedures to disguise the research hypothesis from the subjects ● Experimenter bias is any behavior by the experimenter that can confound the experiment ● Rosenthal effect is the phenomenon in which experimenters treat subjects differently based on their expectations and their resulting actions influence subject performance and confound results ● Doubleblind experiments control both demand characteristics and experimenter bias Personality Variables ● When experimenters are warm and friendly, subjects learn more, talk more, earn better test scores, and are eager to please ● Treat “experimenter” as an independent variable in statistical analysis ● Volunteers are more sociable, score higher in social desirability, hold more liberal social and political attitudes, are less authoritarian, and score higher on intelligence tests than nonvolunteers
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