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Jian Ding, Stanley Klein, Celia Gong, Dennis Levi; Noise alters binocular combination. Journal of Vision 2012;12(9):48. doi: 10.1167/12.9.48.
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When identical sinewave gratings are presented to the two eyes, with noise superimposed in only one eye, the eye with the added noise dominates the binocular combination (Ding and Sperling, 2006, 2007). This surprising result can be accounted for by the Ding-Sperling contrast gain-control model. However, because they only tested limited conditions, the details about how the added noise affects binocular combination remain unclear. In the present study, we examined binocular combination in normal observers using sinewaves with nine interocular contrast ratios (ISCR) and with band-pass noise (1.26 octaves bandwidth) added to both eyes with nine (3x3) different combinations of noise contrast (INCR). The two eyes’ sine waves had identical spatial frequency (SSF) (0.68 cpd or 1.36 cpd) with a 90 deg phase shift, but differed in contrast. The added bandpass noise was perfectly correlated in two eyes. The center frequency of the noise (NSF) was 4 or 8 times that of the sinewaves. We tested a total of 9(ISCR)x9(INCR)x2(SSF)x2(NSF) = 324 experimental conditions. The observer’s task was to indicate the apparent location (phase) of the dark trough in the perceived cyclopean sine wave relative to a black horizontal reference line. The perceived phase was measured as a function of the interocular contrast ratio, which shifted systematically from the left eye to the right eye as the contrast ratio R/L varied from 0.25 to 4. Importantly, the behavior of this phase curve was affected in two ways by the added noise: (1) The phase curve shifted toward the eye to which the stronger noise was added, and shifted back when the identical noise was also added to the other eye; (2) The slope of the phase curve became more shallow (apparent weaker mutual interocular inhibition) when stronger noise was added. These results are well predicted by the Ding-Sperling contrast gain-control model.
Meeting abstract presented at VSS 2012
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