The precise content of grateful beliefs may vary, depending on the nature of the act of beneficence in response to which they are called for.
They may, for instance, include the belief, on Y’s part, that benefactor R is especially brave, or especially thoughtful, or especially self-sacrificing.
They may include the belief, on Y’s part, that R cares a great deal about Y (Berger 1975), and perhaps, relatedly, that Y is worthy of being cared about to such an extent (Shaw 2013, Manela 2019).