Information Greenhouse: Optimal Persuasion for Medical Test-Avoiders

Patients often avoid medical tests because testing produces not only useful information but also painful beliefs. This paper studies optimal communication between a doctor and an information-avoidant patient who first decides whether to take a test and, after an unfavorable result, whether to accept treatment. The doctor can disclose information about how severe non-treatment would be if the patient is sick. The main tension is between warning and reassurance. A warning can make treatment compelling after diagnosis, but reassurance can make testing acceptable by preserving hope about the untreated prospect. I characterize the optimal policy. When the warning that supports treatment is compatible with testing, the doctor uses warning-in-advance. When such warning would deter testing, the doctor constructs an information greenhouse: a committed post-test information environment that reassures the patient about the untreated prospect. With voluntary consultation, reassurance must sometimes be moved before the test as precautionary comfort.