Open Access

Wisanukorn Boribun, Frank Heidmann, Eva Hornecker

• As accuracy and performance increasingly dominate interactive systems, the temporal processes through which human understanding develops often recede into the background. Reasoning unfolds gradually through action, inspection, hesitation, and revision. In this paper, we investigate how embodied reasoning during physical calculation can be made perceptible by attending to how people act, look, and pause while interacting with a material artifact. We present a hybrid sensing prototype centered on a physical abacus that combines gaze, head movement, and bead manipulation to respond to moments of inspection as they emerge. Rather than displaying information continuously or inferring cognitive states, the system briefly surfaces numerical feedback when interaction patterns indicate checking or reflection. Findings suggest that usefulness depended less on what information was shown and more on when it appeared. We argue for interaction aligned with human sense-making rhythms, in which system responses follow observable reasoning activityAs accuracy and performance increasingly dominate interactive systems, the temporal processes through which human understanding develops often recede into the background. Reasoning unfolds gradually through action, inspection, hesitation, and revision. In this paper, we investigate how embodied reasoning during physical calculation can be made perceptible by attending to how people act, look, and pause while interacting with a material artifact. We present a hybrid sensing prototype centered on a physical abacus that combines gaze, head movement, and bead manipulation to respond to moments of inspection as they emerge. Rather than displaying information continuously or inferring cognitive states, the system briefly surfaces numerical feedback when interaction patterns indicate checking or reflection. Findings suggest that usefulness depended less on what information was shown and more on when it appeared. We argue for interaction aligned with human sense-making rhythms, in which system responses follow observable reasoning activity without directing or accelerating it.…