Augmented collaboration in a shared house design scenario has been studied widely with various approaches. However, those studies did not consider human perception. Our goal is to lower the user's perceptual load for augmented collaboration in shared space design scenarios. Applying attention theories, we implemented shared head gaze, shared selected object, and collaborative manipulation features in our system in two different versions with HoloLens. To investigate whether user perceptions of the two different versions differ, we conducted an experiment with 18 participants (9 pairs) and conducted a survey and semi-structured interviews. The results did not show significant differences between the two versions, but produced interesting insights. Based on the findings, we provide design guidelines for collaborative AR systems.