The Double-Blind Procedure Strengthens the Internal Validity of a Study

Multiple Choice

The double-blind procedure strengthens the internal validity of a study because:

A) it creates more confounding variables in the experiment so the experimenter can be assured of validity.
B) it insures that a given sample is representative of the population from which it is drawn.
C) it eliminates the problem of the participants' social desirability bias.
D) it minimizes the effect of experimenter or participant expectations on the outcome of an experiment.