In a classic study on , Rosenthal and Jacobson administered a nonverbal intelligence test to students in a San Francisco elementary school. The students who the teachers were told would show surprising gains achieved greater increases on their test scores.

Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?