Conflicting ordinal and metric depth information interferes with depth matching

Here, we investigate the effects of conflicting metric (binocular disparity) and ordinal (occlusion) depth information. In these experiments a virtual letter "A" was presented using a Microsoft HoloLens 2 optical-see through augmented reality display and was superimposed on a physical occluding surface with variable transparency. Observers performed a depth matching task and, for comparison, performed the same task without the occluder. Our results show that, when the surface was absent, or the letter was rendered in front of the surface, the letter was accurately localized. However, when the letter was rendered beyond the surface, observers progressively underestimated its distance. The magnitude of this error was modulated by the opacity of the occluding surface, but persisted even when additional depth information was provided by retinal size cues. Our results are well modeled using a Bayesian cue combination model with a uniform prior for letter positions in front of the surface and a non-uniform prior with a Gaussian fall-off for letter positions beyond the surface. These findings underscore the strong influence of incorrect occlusion arrangements, capable of distorting perceived depth even when binocular disparity is available.