Effects of Focal Distance on Near-Field Depth Perception and Accommodative Response in a VariFocal Optical See-Through Augmented Reality Display

Through a human-subject experiment, we investigated the effects of focal distance on depth perception and accommodative response in an optical see-through augmented reality (AR) display. The display was able to provide focus cues and was rigorously calibrated. The near-field distances ranging between 3 diopters and 1 diopter were considered as target distance. In the experiment, it was found that the perceived depth of a virtual object was significantly biased along with the focal distance of virtual image plane of the display. In addition, the experimental results implied that the perceived depth of a virtual object would be potentially more accurate in the condition where the focal distance of virtual image plane was consistent with the target distance than in the conditions where it could deviate from the target distance. Regarding accommodative response, it was found that the response to a virtual object changed along with the focal distance of virtual image plane as well as the target distance. However, the changing rate depending on target distance was less steep in the conditions where the focal distance could be mismatched with the target distance than in the condition where it was consistent with the target distance. In the consistent condition, the changing rate of accommodative responses to virtual objects were similar to that for their physical counterparts.