Understanding how we perceive and interact with others is a core challenge of social cognition research. This challenge is poised to intensify in importance as the ubiquity of artificial intelligence and the presence of humanoid robots in society grows. This talk examines how established theories and methods from psychology and neuroscience are revealing fundamental aspects of how people perceive, interact with, and form social relationships with robots. Robots provide a resolutely new approach to studying brain and behavioural flexibility manifest by humans during social interaction. As machines, they can deliver behaviours that can be perceived as “social”, even though they are artificial agents and, as such, can be programmed to deliver a perfectly determined and reproducible set of actions. As development of service robots, home companion robots and assistance robots for schools, hospitals and care homes continues apace, whether we perceive such machines as social agents and how we engage with them over the long term remains largely unexplored. This talk describes research that bridges social cognition, neuroscience and robotics, with important implications not only for the design of social robots, but equally critically, for our understanding of the neurocognitive mechanisms supporting human social behaviour more generally.