This study addresses the paradoxical phenomenon in Western medicine where physicians, despite the foundational principle of honesty, often convey false hope to patients. Grounded in recent developments in behavioral science, we posit that physicians and surrogates systematically undervalue the extent to which patients desire candid medical communication. Additionally, this study also explores the important role of culture in driving these beliefs. Presenting two medical scenarios to physicians recruited in China and the U.S., and non-doctor adults taking patients or surrogates perspectives, we found that both surrogates and doctors often underestimate patient preferences for honesty, especially in discussions about prognosis, with this trend most pronounced in the case of U.S. doctors predicting the preferences of Chinese American patients. In our cross-cultural comparison, while Chinese patients expressed a greater preference for false hope compared to White American patients, this inclination was not observed in the case of Chinese-American patients, a nuance that doctors failed to grasp. Implications for communication and conflict, healthcare management, as well as cross-cultural psychology were discussed.