Abstract
Dichoptic masking was compared between luminance and contrast domains using the modified dichoptic probed-sinewave paradigm. A brief letter (16.6ms) was presented to one eye while a sinusoidally varying (luminance or contrast) masker was dichoptically presented to the other eye. The contrast detection threshold of the letter was measured at various times (phases) with respect to the flickering masks. Three flickering frequencies (1, 2, 3 Hz) and four different types of maskers were used: (1) a large uniform-field luminance-defined masker, (2) an equivalent-sized contrast-defined masker that had a 1/f power spectrum, (3) a small localized contrast masker that covered the letter area only,(4) a surround contrast masker whose area is equal area(2)-area(3). The results showed that luminance maskers generally increased the detecting threshold but not in a luminance-dependent manner. On the other hand, thresholds did vary in a contrast-dependent manner for both (2) and (3). No contrast-dependent modulation was found for (4). Our results suggest that dichoptic masking can come in at least two forms: luminance-based and contrast-based. In the former, dichoptic masking is sustained whereas in the latter it is more localized in time and space.
Meeting abstract presented at VSS 2012