Abstract
Scene perception research often uses visual masks to vary the time that information is available on a viewer's retina. However, little is known about the effects of spatial and temporal masking parameters when masking real-world scenes. Such studies using visual masking often include blank screens at the start of the trial, during the ISI between target and mask, and following the mask presentation. These blank screens are typically black, white, or a neutral gray matched to the mean luminance of the target and mask, with neutral blank screens presumably intended to minimize luminance contrast with the target and mask. Earlier research (Freeman & Loschky, VSS 2009) showed differences between black and gray blank screens at SOAs <24 ms, using 12 ms target durations, with higher contrast black blank screens producing stronger masking. However, with 12 ms target durations, white blank screens produce a floor effect–a flat slope near chance across SOAs. To avoid that, the present study increased target durations to 24 ms and compared the masking effects of white, black, and gray blank screens, with SOAs from 24-96 ms. Results showed that white blank screens produced far greater masking than both the black and equiluminant gray blank screens at all SOAs, but no difference in masking between the black and equiluminant gray blank screen conditions. However, considering the results of Loschky and Freeman (VSS, 2009) it appears that higher contrast black and white blank screens both produce stronger masking than equiluminant gray screens, with white screens producing the strongest masking that persists at longer SOAs. A possible explanation for these results is in terms of on- and off-channels, with the faster on-channels having a greater impact in masking briefly flashed scenes. Thus, the current study provides important information for scene perception researchers using visual masking.