Robustly Non-Harmful Information for Biased Learners

I examine when robustly beneficial information can be provided to a receiver who also learns from misspecified background sources that are outside the provider’s control. In contrast to information provision for rational receivers, any source can be harmful under certain misspecifications of background sources. I show that the key aspect of the background environment enabling robustly beneficial design is the receiver’s perception rather than the true structure. For any background source structure and design of the provided source, there exists a misspecification under which harm occurs. Consequently, even complete knowledge of the true structure is insufficient and knowledge of the receiver’s perception is necessary. Under complete knowledge of the perception, I demonstrate how to design an information source that is robustly non-harmful and often strictly beneficial, regardless of the true background sources.