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Isabelle Mareschal, Joshua Solomon, Michael Morgan; The opposite of crowding revealed using classification images. Journal of Vision 2008;8(6):430. doi: 10.1167/8.6.430.
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© ARVO (1962-2015); The Authors (2016-present)
Observers' acuity for discriminating the tilt of a parafoveal target is hampered by similar stimuli nearby, this is known as crowding. In an attempt to better understand this phenomenon, we obtained classification images for discriminating between ±8° tilted Gabor patterns at 5° eccentricity in two conditions: when presented alone and when appearing in the center of an annularly windowed, vertical grating of similar spatial frequency. To our surprise, performance was better with the annulus. To verify that we could produce crowding in observers, we removed part of the annulus, leaving a ring of eight vertical Gabors, each of which was the same size as the target. Consistent with previous research, acuity was severely hampered by this geometry. Compared with those obtained without an annulus or flanks, the classification images obtained in the presence of the annulus indicate the use of a more oblique and narrower band of orientations. We propose that the strong perceptual border between target and annulus benefits performance by allowing observers to ignore the output of less-informative channels. Given that observers' performance is limited by external noise, our data do not support the theory of improved acuity through disinhibition.
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