Inter-Pupillary Distance Mismatch Does Not Affect Distance Perception in Action Space

Most modern head-mounted displays (HMDs) do not support the full range of adult inter-pupillary distances (IPDs) (i.e., 45 – 80 mm) due to technological limitations. Prior work indicates that the mismatch between a user’s actual IPD and the IPD set in the HMD (“IPD mismatch”) can affect distance and size judgments in near space (0 – 2 m). Therefore, users with IPDs outside of the supported HMD IPD range may not perceive virtual environments (VEs) accurately. Across three experiments, we investigated whether IPD mismatch significantly affects peoples’ distance judgments at longer distances (4 – 7 m). In two of the experiments, we recruited participants with IPDs smaller than the minimum supported IPD of the HTC Vive Pro HMD. They estimated distances in action space using verbal estimation (Experiment 1) and blind walking (Experiment 2) measures in indoor VEs. We found that: (i) distances were underestimated in action space, and (ii) IPD mismatch had minimal to no effect on their distance judgments. In a third experiment, we investigated whether we could generalize our findings to participants with an IPD within the supported HMD IPD range. We were able to replicate our previous findings. Overall, our findings suggest that IPD mismatch in an HMD may not be a major factor in distance underestimation in action space in VEs.