Abstract
Simultaneous lightness contrast (SLC) effects are frequently thought of as perceptual byproducts of low-level retinal interactions, even though high-level processes involved in the perception of depth, 2-D, and 3-D spatial organization have been shown to play an important role in mediating SLC effects. The current study uses a simple dichoptic technique in which a classic SLC display is partitioned so that gray targets are presented to one eye while black and white inducing backgrounds are presented to the other (Cataliotti & Bonato, ARVO 1998). Strong contrast effects were found in some conditions and are consistent with the findings of Anstis and Ho (1998). Under other conditions binocular rivalry interfered with the seamless fusion of the gray targets and their contra-image areas, causing an ambiguous surface color experience (fluttering or luster) of the gray targets. Clear unambiguous fusion and contrast effects were obtained only when the sign of the edge produced by the target-to-surround luminance relationship in the one eye was equal to the sign of the edge produced by the contra-image-to-surround luminance relationship (partial edge correspondence) in the other eye. In these cases we obtained lightness contrast effects that were significantly stronger than those experienced under normal viewing. We also find that as the target's perceived background luminance is systematically manipulated, the slope of the contrast effect is similar under both normal and dichoptic viewing conditions. Overall, these findings suggest that the same or a similarly designed high-level process may be responsible for dichoptic and normal SLC effects.
Supported by NSF Grants; BCS-0196505 and BCS-0002620.