The Effects of Externality Distribution and Framing on Individual Vaccination Decisions: Experimental Evidence

This study examines behavior in a binary choice experiment, designed to characterize the individual vaccination decision. Subjects make choices in each of four one-shot games, differing in the payoff from the “vaccinate†option and the ability of all individuals to choose the “vaccinate†option. Two of the four games include subjects who do not have a choice and automatically receive the “not vaccinate†option. All four games are tested in three different frames: neutral, positive, and negative. In the neutral frame subjects' choices and associated payoffs are presented with no direct mention of the externalities they create. In the positive frame the instructions emphasize the positive externalities created by choosing the “vaccinate†option, and in the negative frame the instructions emphasize the negative externalities created by choosing the “not vaccinate†option. Initial results indicate that subjects choose the “vaccinate†option more often when it yields a certain payoff, or when some of the subjects cannot choose to “vaccinate†. Overall, subjects choose to “vaccinate†most often in the negative frame, followed by the positive frame, and then the neutral frame.