Abstract
Binocular combination of second-order stimuli can be explained by the DSKL model with monocular rectification (Ding & Levi 2017). However, it is unclear whether binocular-combination of second-order stimuli depends on the correlation of the two-eye's first-order carriers. Here, we provide evidence for correlation-dependent interocular interaction. Dynamic bandpass noise was presented to each eye separately using a mirror-stereoscope while a signal, a contrast-modulated (CM) grating (0.68 cpd), was presented to one of the two eyes. The noise had a central-spatial-frequency of 5.44 cpd and was updated every 50 ms with a stimulus duration of 200 ms. In different trials the noise was either correlated, uncorrelated or anti-correlated in the two eyes. The observer's task was to detect the CM grating in the binocularly-combined image by judging its orientation (either left- or right-oblique). The eye with the signal had carrier contrast (CC) of either 0.1 or 0.2, and the other eye (without signal) had CC of 0, 0.25, 0.5, 1, or 2 times of that of the signal eye. Separately, we determined each observer's sighting eye dominance. The results, averaged across four observers with normal binocular vision, show that the CM detection threshold was independent of interocular correlation when the signal was presented to the non-dominant eye. However when the signal was presented to the dominant eye and the other eye's CC was two times the CC of the signal eye, the CM detection threshold was significantly higher (p < 0.033 when CC = 0.1; p < 0.001 when CC = 0.2) when noise in the two eyes was correlated than when it was uncorrelated or anti-correlated. This phenomenon can be interpreted by a modified DSKL model with an additional term of correlation-dependent NDE-to-DE interaction, e.g., with larger NDE-to-DE suppression or less NDE-to-DE enhancement when the two eyes' images are correlated.
Meeting abstract presented at VSS 2018