SOLVING PROBLEMS: CONTROLLING EXTRANEOUS VARIABLES

• Emily faced challenges in her memory experiment due to changing testing conditions.

• The reading room closure led her to test subjects in the building's lobby, introducing potential confounds.

Aspects of testing conditions requiring control.

Technique to control extraneous variables by removing them from the experiment.

Procedure to avoid confounding by keeping treatment conditions identical, except for the manipulated independent variable.

Technique to distribute the effects of extraneous variables equally across treatment conditions.

Eliminate extraneous variables when…

Keep treatment conditions as similar as…

Balance effects of variables evenly across…

Randomly assign individual subjects to…

Prioritize internal validity over external validity in…

External validity relies on first ensuring…

Qualities of relationships between subjects and experimenters influencing experiment results.

• Aspects of the experimental situation eliciting specific behaviors.

• Cues influencing a subject’s response inadvertently.

Subjects unaware of their treatment conditions to control demand characteristics.

Improvement in condition from inert treatment due to expectations or increased motivation.

False explanation of procedures to disguise the actual hypothesis.

Any experimenter behavior creating confounding.

Neither experimenter nor subjects know treatment conditions, controlling experimenter bias.

Personal characteristics brought by an experimenter or volunteer subject to the experimental setting.

Titles may bias samples, reducing…

Non-random subject selection leads to biased samples and less…

Be aware of practice and fatigue effects during…