CAAD Futures 2011 : Designing Together, ULg, 2011 © P. Leclercq, A. Heylighen and G. Martin (eds) 751 Change Detection in 3D Parametric Systems : Human-Centered Interfaces for Change Visualization NASIROVA Diliara, ERHAN Halil, HUANG Andy, WOODBURY Robert and RIECKE Bernhard Simon Fraser University, Canada dnasirov@sfu.ca, herhan@sfu.ca, huang_a@sfu.ca, robw@sfu.ca, ber1@sfu.ca Abstract. Research on current parametric modeling systems is mainly concerned with the underlying computational technology and designs produced, with less emphasis on human factors and design tasks. In these systems, users’ attention is divided on system-imposed actions such as tool selection and set-up, managing obscured views, frequent view manipulation, and switching between different types of representations. In essence, control of the system can become more demanding than the design task itself. Thus, we argue that this unbalanced emphasis inhibits one of the most important functions of parametric design : agility in exploration of design alternatives by applying frequent user-introduced or system-generated changes on the parametric design models. This, compounded by growing complexity of the models and the effect of cognitive limitations such as change blindness, hinders change control and imposes an unnecessary cognitive load in design. In this paper, we made a first step in investigating users’ visual cognitive challenges in the context of parametric design. The main research question is to understand if change blindness significantly influences designers’ performance to detect and localize changes on a variety of models with different placement of change visualization on interfaces. Quantitative and well as qualitative results suggests that change blindness indeed occurs in this scenario and likely reduces designers’ performance by making change detection highly challenging, slow and confusing. Hence, change blindness should be considered as an important factor in designing user interfaces that more effectively support the human designer to focus on the design task, while offloading other tasks to the system and getting adequate support from the computer.