When the contrast polarity in the two input pictures is of opposite sign, the dichoptic combination of simple center-surround stimuli presenting a contrast difference between eyes can provide a glossy impression in the fused percept. 

Recent research suggested that the neurological conflict between ON and OFF visual pathways at an early binocular level was the cause of the phenomena known as binocular luster. Earlier research that showed a good correlation between empirical luster judgments and the predictions of an interocular conflict model based on such ON-OFF pairings provided evidence in favor of this theory. However, the initial model could not account for the fact that stimuli displaying contrast polarity of the same sign between eyes might elicit weaker lustrous feelings. Researchers provided an enhanced model in the current work that additionally considered ON-ON and OFF-OFF pairings. Using a total of around 500 distinct center-ring-surround combinations as test stimuli, the model’s prediction ability was examined in a series of four tests. 

Overall, the improved version explained more than 80% of the variance in the empirical luster judgments, and the earlier issues were mostly overcome. The findings indicated that the binocular conflict signals are transduced nonlinearly.

Reference: jov.arvojournals.org/article.aspx?articleid=2783629