A researcher assesses participants' attitude toward marijuana, presents them with a persuasive communication favoring liberalization of marijuana laws, and then reassesses their attitude toward the drug. However, between assessment 1 and assessment 2, the President also advocates liberalization of marijuana laws. If the researcher doesn't use a control group, any differences that he or she observes are likely to be caused by _____ effects.
A)maturation
B)history
C)regression
D)testing

Question

Quizplus · Accepted Answer

The President advocating liberalization of marijuana laws is a historical event that could influence participants' attitudes, regardless of the persuasive communication presented by the researcher. Therefore, without a control group, any observed differences may be due to the influence of this external event, which is a history effect.

A Researcher Assesses Participants' Attitude Toward Marijuana, Presents Them with a Persuasive