5. • ELIMINATION AND CONSTANCY
To make sure that an extraneous variable does not effect an
experiment, sometimes we just take it out– we eliminate it.
Constancy of conditions means that we keep all aspects of the
treatment conditions as nearly similar as possible.
• BALANCE
Distributing the effects of an extraneous variable across the
different treatment conditions of the experiment.
8. CONTROLLING DEMAND CHARACTERISTICS: SINGLE-BLIND EXPERIMENTS
Single Blind Experiment is an experiment in which subjects do not know
which treatment they are getting.
Placebo Effect is the result of giving subjects a pill, injection, or other
treatment that actually contains none of the independent variable.
9. CONTROLLING DEMAND CHARACTERISTICS: COVER STORIES
Cover Story a plausible but false explanation of the procedures in an
experiment told to disguise the actual research hypothesis so that
subjects will not guess what it is.
10. • EXPERIMENTER BIAS
The influence of what the experimenter does that creates
confounding in the experimenter
11. CONTROLLING EXPERIMENTER BIAS: DOUBLE-BLIND EXPERIMENT
An experiment in which neither the subjects nor the experimenter
know which treatment the subjects are in; used to control experimenter
bias.
*Rosenthal Effect/Pygmalion Effect