Présentation de Josselin THUILLIEZ, CNRS, CREM
**Ineffective Reminders?** In the short term, reminders are considered highly effective in improving various preventive health behaviors, characterized by an immediate action cost for delayed benefits. However, the long-term effects and optimal frequency remain uncertain. We propose a very simple model in which the marginal return of an additional reminder decreases, while fatigue increases over time and with the number of reminders. The race between costly cumulative efforts and the informational and attentional benefits of reminders determines individuals' protection levels in the short and long run. In the short term, increased prevention use is favored by a higher marginal return of information compared to its cost, while in the long term, the rise in fatigue due to this information leads to a decrease in its usage. We next focus on insecticide-treated bednets to prevent malaria, a technology that is highly effective when widely adopted and generates positive health externalities. We combine surveys, unique high-frequency data on net usage with a randomized experiment using generic and specific reminders. We find that while malaria targeted messages are effective in the short term, they have little effect in the long term. Moreover, the higher the frequency, the less effective the reminders are.