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Weina Zhu, Jan Drewes, David Melcher; Mechanisms of suppression: How the classic Mondrian beats noise in CFS masking. Journal of Vision 2017;17(10):141. doi: https://doi.org/10.1167/17.10.141.
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In a typical Continuous Flash Suppression (CFS) paradigm (Tsuchiya & Koch, 2005), a series of different "Mondrian" patterns is repeatedly flashed to one eye, suppressing awareness of the image presented to the other eye. In our previous study (Zhu, Drewes, & Melcher, 2016), we found that the spatial density of the Mondrian patterns affected the effectiveness of CFS. To better understand this finding, we varied the shape and edge information in the mask. Typical Mondrian-style masks are made from individual rectangular patches, resulting in sharp horizontal and vertical edges between neighboring luminance levels. To investigate the role of these edges, we compared grayscale Mondrian masks with various noise patterns as well as phase-scrambled Mondrian equivalents and "Klee" masks (a type of pink noise mask with edges). We employed a breakthrough CFS paradigm with photographic face/house stimuli and a range of temporal masking frequencies (3-16Hz). The noise patterns were white noise with spatial frequency filtering applied, resulting in noise spectra ranging from 1/f0.5 to 1/f10. Subjects (N=16) were instructed to press the button as soon as they saw any part of the stimulus. Results show that the most effective mask was the classic Mondrian. Among the noise masks, pink noise (1/f1) lead to longer suppression while the least effective masking was achieved by 1/f10 noise. Interestingly, the masking effectiveness of the phase-scrambled Mondrian masks as well as the "Klee" masks was not significantly different from pink noise. Adding edges to noise masks therefore did not significantly improve masking effectiveness. Phase scrambling the Mondrian patterns did significantly reduce their effectiveness. The remaining advantage Mondrian masks have over random noise patterns may result from the higher effective contrast range or presence of surface shapes afforded to the Mondrians by the patchwork design.
Meeting abstract presented at VSS 2017
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