A web-based contingent behavior analysis was developed to quantify the effect of both negative and positive information treatments and post harvest processes on demand for oysters. Results from a panel model indicate that consumers of raw and cooked oysters behave differently after news of an oyster-related human mortality. While cooked oyster consumers take precautionary measures against risk, raw oyster consumers exhibit optimistic bias and increase their consumption level. Further, by varying the source of a counter-information treatment, we find that source credibility impacts behavior. Oyster consumers, and in particular, raw oyster consumers, are most responsive to information provided by a not-for-profit, nongovernmental organization. Finally, post harvest processing of oysters has no impact on demand.