Architects are sometimes criticised for prioritising aesthetics over functionality; but attempts to involve end users in building design all too often encounter apathy. Is a successful participatory design process possible? Carlo Ratti and Matthew Claudelof MIT's Senseable City Lab have been researching ways to make it so. Their solutions include an adaptation of the A/B testing method used in software development, together with means from questionnaires to immersive virtual systems that can draw both conscious and unconscious public feedback while maintaining architects' central role.