How does the presence of an audience influence the social interaction with a conversational system in a physical space? To answer this question, we analyzed data from an art exhibit where visitors interacted in natural language with three chatbots representing characters from a book. We performed two studies to explore the influence of audiences. In Study 1, we did fieldwork cross-analyzing the reported perception of the social interaction, the audience conditions (visitor is alone, visitor is observed by acquaintances and/or strangers), and control variables such as the visitor’s familiarity with the book and gender. In Study 2, we analyzed over 5,000 conversation logs and video recordings, identifying dialogue patterns and how they correlated with the audience conditions. Some significant effects were found, suggesting that conversational systems in physical spaces should be designed based on whether other people observe the user or not.