Stress-related writing has been found to be beneficial for patients with either HIV infection or cancer. This is an example of the effectiveness of:

a. hypnosis.
b. emotion expression.
c. relaxation training.
d. mindfulness meditation.

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?