Nearly 20 years ago, Gaver et al. introduced ambiguity as a design resource, proposing tactics to reflect everyday uncertainty into interactive systems. This approach is especially relevant for self-tracking wearables, which often obscure the inherent ambiguity of system design and tracked phenomena with seemingly clear, prescriptive data and insights. Although scholars recognize the importance of ambiguity, its practical application in the design process remains underexplored. To address this, we conducted a two-week workshop with 60 designers, examining the application of Gaver et al.’s tactics into 11 design concepts, and performed interviews with 16 participants. Our findings reveal eight relevant ambiguity tactics for self-tracking and offer insights into participants’ experiences with designing using ambiguity. We discuss prescription and overlooked ambiguity as levers for the operationalization of ambiguity, the potential benefits and downsides of ambiguity tactics for users, future directions for HCI research and practice, and the study limitations.

Ambiguity is gaining attention in self-tracking research as a means to go beyond the mere quantification of body signals. Recent research has suggested that ambiguity can be used even to enable social connection mediated by personal data. To explore this design space more widely, we organized two design workshops with a total of 67 participants. In this paper, we present three design concepts, as outcomes of the workshops, which use ambiguity to enable social self-tracking practices. We then discuss how these concepts demonstrate the potential of ambiguity to encourage collective sense-making, directly impact the user's social relationships, and offer multifaceted perspectives on reality.