The behavior motivation hypothesis was supported in this longitudinal study, but the opposite conclusion (i.e., that higher risk led to less protective behavior) would have been drawn from an incorrect test based only on cross-sectional data. Health researchers should take care in formulating and testing risk-perception-behavior hypotheses.

Hypotheses generated by the precaution adoption process model, a stage model of health behavior, were tested in the context of home radon testing. The specific idea tested was that the barriers impeding progress toward protective action change from stage to stage. An intervention describing a high risk of radon problems in study area homes was designed to encourage homeowners in the model's undecided stage to decide to test, and a low-effort, how-to-test intervention was designed to encourage homeowners in the decided-to-act stage to order test kits. Interventions were delivered in a factorial design that created conditions matched or mismatched to the recipient's stage (N = 1,897). Both movement to a stage closer to testing and purchase of radon test kits were assessed. As predicted, the risk treatment was relatively more effective in getting undecided people to decide to test than in getting decided-to-act people to order a test. Also supporting predictions, the low-effort intervention proved relatively more effective in getting decided-to-act people to order tests than in getting undecided people to decide to test.

Percentage and frequency formats facilitate performance of simple operations on risk probabilities compared with the 1-in-n format, which should usually be avoided.

We found some evidence of regression (protective behaviors dropping, after vaccination, to levels reported by the unvaccinated cohort). However, we did not find disinhibition (exceeding the risk taking of the unvaccinated cohort), the greater threat to public health. Although we will not know for several years what effect HPV vaccination has on other behaviors, if any, data on other vaccinations can offer critically important information in the interim.

No abstract