Comparative assessment of spatial perception in augmented reality depending on the consistency of depth cues

Discrepancies between depth cues (accommodation and vergence) is one of the major issues caused in a stereoscopic augmented reality at close viewing distances. It adversely affects not only user comfort but also spatial judgements. Images with consonant cues at different distances have become available due to the implementation of multifocal architecture in the head-mounted displays, although its effect on spatial perception has remained unknown. In this psychophysical study, we investigated the effects of consonant and conflicting depth cues on perceptual distance matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in two modes: multifocal mode and single-focal plane mode. The participants matched the distance of a real object with the images projected at three viewing distances (45 cm, 65 cm, and 115 cm). As a result, no significant differences in the accuracy of spatial perception were shown depending on the consistency of cues. However, the perceptual tasks were completed faster when the depth cues were consonant. Overall, the results of our experiment show that consonant depth cues facilitate faster judgements on spatial relations between real objects and images projected in augmented reality, which can be achieved when images are displayed using multiple depth planes in the head-mounted display. Further technological advancements might be required to improve the accuracy of spatial judgements in augmented reality.