Background <p>Visualizing the deformation of hydrogels at sliding interfaces remains challenging due to their optical transparency, limiting our understanding of time- and history-dependent surface displacement during continuous sliding.</p> Objective <p>To visualize and quantify the lateral surface displacement of hydrogel during continuous sliding and correlate this with frictional behavior.</p> Methods <p>Fluorescent markers were embedded in hydrogel samples to enable visualization of surface deformation during sliding. Marker positions were recorded via video and tracked across frames, allowing extraction of time-varying displacement of the hydrogel surface in the sliding direction. The surface displacement was measured at various sliding speeds and compared with friction measurements from tribo-rheometry experiments.</p> Results <p>The visualization technique successfully revealed significant time- and history-dependent lateral surface displacement in the hydrogel during continuous sliding. The calculated surface displacement over time at different speeds showed patterns that closely resembled the frictional behavior measured in tribo-rheometry experiments, providing direct visual evidence of surface mechanics.</p> Conclusions <p>This work establishes a correlation between visually observed surface displacement and measured friction in hydrogels, supporting the previously proposed rate-and-state hydrogel lubrication model.</p>