Reflection is a recurring notion in the HCI/interaction design literature. Throughout the years reflection has been highlighted as a key dimension of design thinking and as an important ingredient of design processes. In this paper we take stock in our community's interest in reflection, and we suggest that while it has been acknowledged as a cornerstone for design processes, it has been less explored as a basis for design outcomes. Given this extensive literature study, it seems that 1) the interest in this area is growing, and we present tables that illustrate this growing interest over time; 2) reflection and behavioral change are two interrelated notions; and 3) these notions are well-explored in our field. Further, we suggest that as interaction design is increasingly exploring the design of tangible, smart, connected, and even intelligent artifacts, we should think about how reflection and our ability to think with artifacts can be extended to include the design of interactive artifacts. In this paper we suggest how that might be done, and we point at a design space for designing such interactive artifacts to think with.