We present here a pilot study of child-robot interactions, in which we discuss developmental origins of human interpersonal communication. For the past few years, we have been observing 2- to 4-year-old children with autism interacting with Keepon, a creature-like robot that is only capable of expressing its attention (directing its gaze) and emotions (pleasure and excitement). While controlled by a remote experimenter, Keepon interacted with the children with its simple appearance and actions. With a sense of curiosity and security, the children spontaneously approached Keepon and engaged in dyadic interaction with it, which then extended to triadic interactions where they exchanged with adult caregivers pleasure and surprise they found in Keepon. Qualitative and quantitative analysis of these unfolding interactions suggests that autistic children possess the motivation to share mental states with others, which is contrary to the commonly held position that this motivation is impaired in autism. We assume Keepon's minimal expressiveness helped the children understand socially meaningful information, which then activated their intact motivation to share interests and feelings with others. We conclude that simple robots like Keepon would facilitate social interaction and its development in autistic children.