Antonella Pavese has some interesting things to say in a piece called The social life of humans and machines: How to design for the social interaction | AntonellaPavese.com

"Designing an interface for a successful social interaction is not about adding faces, voices, and injected personalities. It's not about using chat, videoconferencing, or other fancy technological tools. It's about being able to recreate the social experience that satisfies people's need to be listened to, guided, persuaded, cheered, and reassured. When we started paying attention to the qualities of the social experience, a miracle happened: people started to love our design."