Abstract
Binocular vision requires combining two eye’s views into a single percept of the world. The rules that govern binocular combination can be studied by showing people dichoptic stimuli (stimuli that have differing appearance in the two eyes) and using an adjustment task to identify the most closely matching non-dichoptic stimulus. However, oftentimes the perception of dichoptic stimuli is a unique experience and is challenging to precisely match. A common example of this is the binocular rivalry experienced when viewing orthogonally oriented gratings in the two eyes. While rivalry is well-studied, less is known about the subjective appearance of stimuli with the same spatial pattern but different contrasts in the two eyes. Understanding perception of these more subtle dichoptic stimuli is relevant for the development of stereoscopic displays, in which interocular differences in color and contrast may occur either intentionally or unintentionally. In this study, we asked people to match a dichoptic and non-dichoptic stimulus as closely as possible in visual contrast. We then asked follow-up questions to better understand any remaining differences in appearance. Participants compared the stimuli in their overall brightness, contrast, luster, alternation over time (rivalry), and depth. We found that: (1) both dichoptic gratings and noise were less likely to have an exact match as the interocular contrast difference increased, (2) noise stimuli were overall less likely to have an exact match compared to gratings, (3) when an exact match could not be obtained, people tended to see luster and rivalry, with gratings more likely to be rivalrous and noise more likely to be lustrous, and (4) differences in perceived brightness, contrast, and depth were also common. These results suggest that the perception of dichoptic stimuli is multifaceted, such that contrast differences in stereoscopic displays have potential to be both problematic and beneficial.