Abstract
We have recently proposed that objects in the lower visual field (LVF) are closer to the observer’s eyes than those in the upper visual field (UVF) and this was supported by a quantitative analysis of visual inputs during naturalistic behavior with LVF inputs consistently closer across environments (75%-95% of the time). Investigating how this visual input LVF-UVF asymmetry was reflected in perception revealed a significant perceptual bias of closer LVF judgments (at LVF-UVF equidistant condition there were 5 times more ‘LVF closer’ responses than ‘UVF closer’, n=192). Since this was found in 2D displays, we further wanted to examine if this perceptual bias is also present during naturalistic 3D vision affording oculomotor and stereo information. 35 participants (aged 18–40, normal vision) underwent a realistic VR experiment (110 trials, indoor, urban and forest environments, 2 marked targets (in LVF and in UVF) per trial) and were asked to judge which target was closer. Similar to the 2D experiment, in the 3D VR equidistant condition we found a significant ‘closer LVF’ bias (p<0.001). However, the proportion of ‘lower closer’ relative to ‘upper closer’ judgements in the 3D VR critical equidistant condition (2:1) was smaller than that found in the 2D experiment (5:1). Our results of a perceptual bias of closer LVF that cannot be completely overcome by stereo or oculomotor cues may be explained by our finding that in naturalistic ‘in the wild’ vision objects in LVF are significantly closer to our eyes than those in the UVF.