Research by Leventhal and his colleagues (1967) was described in the text. In the experiment, the researchers showed some smokers a graphic film about lung cancer and gave them a pamphlet with instructions on how to quit; other smokers received either the pamphlet alone, or watched the grisly film. After three months, those smokers who received only the pamphlet with instructions were smoking significantly more than those who both saw the film and received the pamphlet. What is the independent variable of this research?

Leventhal et. al. describes the fear drive model as a variant of the classic drive reduction model used in animal studies. The paradigm they were testing "assumes that the communication produces both persuasion and fear; fear does not cause persuasion. The chapter reviews the evidence regarding interactions between the level of fear elicited by the communication and other factors such as personality variables and recommendation effectiveness."

The amount that they smoked was not a dependent or key variable in the study.

Reference: Leventhal, Howard.. “Findings and Theory in the Study of Fear Communications.” ScienceDirect, Academic Press, 10 Apr. 2008