Chp8 Final

Physical Variables Social Variables Personality Variables Context Variables

What are physical variables?

Physical variables are aspects of the testing situation that need to be controlled: 

day of the week

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experimental room lighting

 

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Physical Variables

Explain elimination.

Elimination completely removes extraneous physical variables from the experimental situation (e.g., soundproofing a room). Removal of extraneous physical variables prevents them from operating differently across different treatment conditions.

Physical Variables

How does constancy of conditions work?

Constancy of conditions controls extraneous physical variables by keeping all aspects of the treatment conditions identical, except for the independent variable. For example, test all subects in the same room or at the same time of day.

Physical Variables

How does balancing work?

Balancing controls extraneous physical variables by e!ually distributing their effects across treatment conditions. For example, running half of the subects in each condition in the morning and half in the evening.

Physical Variables

In which order shold yo se these techni!es?

". #liminate extraneous variables whenever possible. $. %eep conditions constant where elimination is not possible. &. 'alance the effects of extraneous variables when constancy of conditions is not possible.

Physical Variables

What are social variables?

Social variables are aspects of the relationships between subects and experimenters that can influence experimental results. hese include demand characteristics and experimenter bias.

"ocial Variables

Explain demand characteristics.

Demand characteristics are cues within the experimental situation that demand or elicit specific participant responses. #xample: students cue professors to wrap up their lectures by packing their binders, books, and water bottles, and by looking at the door.

"ocial Variables

How can demand characteristics threaten internal validity?

emand characteristics can confound an experiment if they vary across experimental conditions. *ubects may act to confirm what they think is the experimental hypothesis.

"ocial Variables

What is a single#blind experiment?

+n a single-blind experiment , subects are not told their treatment condition. For example, in a singleblind drug study, the experimental and control groups might receive capsules that look and taste identical.

"ocial Variables

How do single#blind experiments control demand characteristics?

-hen subects are not told their treatment condition, this eliminates cues that might alter their behavior.

"ocial Variables

What is the placebo effect?

he placebo effect is when a subect receives an inert treatment and improves because of positive expectancies.

"ocial Variables

How do cover stories control demand characteristics?

  cover story is a false plausible explanation of the experimental procedures to disguise the research hypothesis from the subects. hey should be used sparingly, since they are a form of deception.

"ocial Variables

What is experimenter bias?

Experimenter bias is any behavior by the experimenter that can confound the experiment. For example, an experimenter might provide more attention to subects in one condition than another.

"ocial Variables

What is the $osenthal effect?

he Rosenthal effect is the phenomenon in which experimenters treat subects differently based on their expectations and their resulting actions influence subect performance. his is also called the Pygmalion effect and self-fulfilling prophecy .

"ocial Variables

What is the $osenthal effect?

For example, teachers might give more attention and feedback to high aptitude students than to low aptitude students. he Rosenthal effect can confound an experiment, producing results consistent with the experimenter/s expectations.

"ocial Variables

Why is a doble#blind design sperior to a single# blind design in controlling experimenter bias?

Single-blind experiments only control demand characteristics, since subects are blinded to their condition. Double-blind experiments control both demand characteristics and experimenter bias, since both the experimenter and subects are blinded.

"ocial Variables

How might an experimenter%s personality affect experimental reslts?

Research on experimenter personality shows that when experimenters are warm and friendly, subects learn more, talk more, earn better test scores, and are eager to please. 0ostile or authoritarian experimenters obtain inferior subect performance.

Personality Variables

How can experimenters control personality variables?

#mploy multiple experimenters to run an e!ual number of subects in each of the experimental conditions (balancing). reat 1experimenter2 as an independent variable in statistical analysis. +f an interaction is found, then the experiment was confounded.

Personality Variables

How can experimenters control personality variables?

-hen there is a single experimenter, minimi3e facetoface contact and closely follow the script. 4ideotape sessions to confirm consistent performance.

Personality Variables

How do volnteers differ from nonvolnteers?

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.

Personality Variables

What are context variables?

Context variables are extraneous variables produced by experimental procedures created by the research setting environment, like assignment of participants to conditions.

&ontext Variables

When might sb'ects select the experiment?

-hen we allow subects to sign up for experiments whose titles differ in their appeal: 1he 5emory est #xperiment2 1he 0eavy 5etal 5usic #xperiment2 0owever, this could result in a biased sample threatening external validity .

&ontext Variables

Why sholdn(t yo rn yor friends in yor experiment?

*electing your friends might bias your sample, threatening external validity. 'oth you and your friends might act differently in your experiment than strangers.

&ontext Variables

"mmari)e the folklore abot sb'ects.

*ubects who sign up late in the semester may be less motivated and may behave differently than those who sign up earlier in the semester. Rosenthal speculated that the differences seen at the start and end of an experiment may be  ust as likely due to changes in the experimenter.

&ontext Variables