The encounter of ideas, beliefs and representations is integral to the history of human cultures and all public spheres are created in communicative spaces where people exchange views and practices about the world. The history of all cultures is made of cultural borrowings (Said, 1978) because since times immemorial ideas have travelled and mixed, exposing human communities to the thoughts, perspectives and preconceptions of unfamiliar others. The unfamiliar has never been too far away and is a central motivation in the production of knowledge. Today, increasing world-wide interconnectivity and novel mass media of communication make this process more visible than ever and accentuate questions about what happens when different systems of knowing travel and meet in public spheres. Is the world becoming too homogeneous as more powerful representational systems displace others? Is heterogeneity in social life enabling a rich and diverse public sphere? Or is the confluence of differences producing fragmentation and exclusion? How do we treat what is unfamiliar and different? And how do these issues affect our social representations and ways of thinking about our social worlds? Addressing these questions requires understanding how social representations are formed and interact in public spheres. This was a central problem in Moscovici's original study on the reception of psychoanalysis in France. Its design and execution constitute a paradigmatic example of how to explore social representations as phenomena of the public sphere. This study showed that as psychoanalysis moved between different communities through multiple modalities of communication it became a public entity, an object of discussion, contestation, and ultimately widespread knowledge. Apprehending how the plurality inherent in human public spheres shapes knowledge outcomes and the structure of representational fields is at the core of studies of social representations. Different people, in different contexts and historical periods within and across cultures, produce different representations, symbols and narratives about what is real. Mapping out these variations has been central to sociocultural approaches to cognition (Cole, Engestrom and Vasquez, 1997).