Virtuals

Three works by Poul Anderson feature virtual realities experienced by AI programs which think that they are human beings. However, Anderson did not write any story about such programs beginning to doubt the reality of their perceived environments. That kind of existential question is the province of Philip K. Dick.

In Anderson's Genesis, two uploaded personalities are in no doubt as to the nature of their "emulated" environment. However, each of these personalities remains a conscious and intelligent being able to converse with the other through an emulated body as effectively as s/he had been able to converse with other human beings using a material body when alive.

On the other hand, each upload is a copy of the personality made shortly before his or her physical death. If that original self-conscious individual survived into a hereafter, then the surviving soul is different from the uploaded copy.