Selectivity of second-order visual mechanisms sensitive to the orientation modulations revealed by masking M Miftakhova, V Babenko, D Yavna |
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Department of Psychology, Southern Federal University, Russian Federation
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| Second-order visual mechanisms process information on modulations of primary visual features such as contrast, orientation and spatial frequency. Here we show psychophysical research of visual mechanisms sensitive to the orientation modulations. Test stimulus has a carrier that is texture composed of horizontally oriented staggered Gabor micropatterns, and envelope that is sinusoidal modulation function of orientation. Masks are test textures with different envelope shifts in: i) phase (0-180 deg), ii) orientation (0-90 deg), iii) spatial frequency (from -2 to +2 octaves). Using masking, 2-alternative forced-choice procedure, and staircase method we revealed bandpass tunings of mechanisms in question to orientation, phase, and spatial frequency of modulation. Spatial frequency selectivity is consistent with some current data [Reynaud and Hess, 2012, Exp Brain Res, 220(2), 135-145; Westrick et al, 2013, Vision Res, 81, 58-68], but is inconsistent with our previous results obtained in analogous study using stimuli with vertical orientation of a carrier [Babenko et al, 2012, Proceedings of 10th International Conference "Applied Optics", P. 331-334]. We suppose that this discrepancy in results is due to the fact that in 2 experiments there are different ratios of carrier-envelope orientations, and these ratios play important role in perception of second-order orientations. |
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