The motif of the talking head is found in both folklore and literature. In the synodical literary prefaces, there are several texts with such a motif. All of them belong to the symbolic genre of miracle. The most famous of them is the conversation of the Reverend Macarius with the skull of the idol priest. The other two miracles describe events that happened to a robber and a warrior, whose heads were able to confess after death, since their owners venerated the Holy Mother of God during their lifetime. Miracles about talking heads served as visual examples in the synodikon, illustrating the importance of prayer for the dead and the need to prepare for Eternal Life.
E.S. Shadrina (Thu,) studied this question.