Chaeeun Lim¹, Dhanraj Vishwanath², Fulvio Domini¹; ¹Brown University, ²University of St. Andrews

Systematic biases in distance and depth perception distort the perceptual map of 3D space. Can such biases be actively updated by physical interaction? To address this, we leveraged a specific bias identified in our previous research (Lim, Vishwanath, & Domini, 2025). While standard theories posit that egocentric distance is required to scale exocentric depth, our findings suggest a bidirectional relationship: systematic biases in exocentric depth estimation also distort the perception of egocentric distance. We demonstrated this using stereoscopic paraboloids where the back of a near object (near-back) physically aligned with the front of a far object (far-front). Due to typical depth overestimation in near space, the near-back appears significantly farther away than the far-front. This creates a "spatial discrepancy" where physically equidistant points are perceived at different distances. Here, we investigated whether sensorimotor interaction could correct this discrepancy. In a pre-test where participants estimated the near-back and far-front surface locations relative to a reference stimulus, the spatial discrepancy was replicated: the near-back was judged as significantly farther than the far-front, despite being physically collocated. Participants then performed a learning task, reaching to touch both surfaces with haptic and visual feedback. This signaled that the perceptually distinct near-back and far-front were actually at the same distance. A post-test—identical to the pre-test—revealed that the spatial discrepancy was significantly reduced following learning, unlike in a control group. It is striking that this learning from a short-term (72 trials) visuomotor task transferred to a pure perceptual task involving no motor response. This reduction in bias could not be due to simple visuomotor adaptation but a result of a fundamental rescaling of the perceptual 3D map. These findings demonstrate that the visual system actively utilizes sensory feedback to correct intrinsic biases, updating the perception of space itself.

Acknowledgements: This material is based upon work supported by the National Science Foundation under Grant No.2120610.