People adapt their word choice to both humans and computers. In this study, language style (elaborated vs. restricted) and perceived conversational partner (human vs. spoken dialogue system) were varied. Convergence was greater when reacting to a restricted language style. Participants preferred human partners and an elaborated language style. In line with communication accommodation theory, results suggest that considering restricted capabilities (cognitive organization) constitutes a central motive for convergence. Implications for spoken dialogue system design are discussed.