Although rudimentary memory systems for
autonomous agents have existed for quite a while, human-like memory systems which contain extensive episodic, social and affective components, and which can be utilized in order to maintain relationships with humans, have only recently started to appear. Interactive robots are a special case of an autonomous agent, which is physically situated, interacts with humans, and
which has sensing and motor abilities. Furthermore, social robots might have regular encounters and interactions with other human
or non-human entities, and might maintain relationships with them. In this paper, a set of desiderate for memory systems of companions will be presented, together with case studies of the memory subsystems of two existing robotic systems: first, Ripley the Robot, an interactive manipulator robot arm with vision, dialogue, and a sensorymotor-grounded situation model;
and second, Sarah the FaceBot, a social mobile robot with face recognition, dialogue, as well as a social and interaction database which is bi-directionally connected to the FaceBook website. The case studies provide the basis for an interesting discussion involving physical situations, self-models, expectations, and
most importantly episodic and social memories, human- or machine- authored, internal or external, private or shared.