Ülker Tulunay-Keesey's research while affiliated with University of Wisconsin–Madison and other places

Publications (6)

Article
The addition of a uniform increment of luminance (L) to a faded retinally-stabilized target results in the subjective reappearance of the image with contrast opposite to that of the target. This phenomenon, called apparent phase reversal (APR), reveals a nonlinear gain mechanism in the adaptation process. The magnitude of the threshold increment to...
Article
Fading time of a retinally-stabilized difference-of-Gaussian (DOG) stimulus depends on the background luminance, contrast and spatial frequency content of the stimulus. A model of the visual system including a nonlinear multiplicative, non-local and fast process followed by a linear subtractive, local and slower process accounts for these effects....
Article
It is well known that targets whose images are stabilized on the retina by optical means, as well as afterimages that are naturally stabilized on the retina, fade and eventually disappear. Comparative data are presented on the rate of disappearance of stabilized images and afterimages as a function of contrast and spatial frequency. The main findin...
Article
Recently, it has been argued that the precision of image stabilization is reflected in the magnitude of the differences in contrast sensitivity measures obtained with and without image stabilization. Here we present two sets of data, one showing large and the other small differences in contrast sensitivity to sinusoidal gratings viewed under stabil...
Article
Spatial sinusoidal gratings were viewed under both stabilized and unstabilized viewing conditions. They were presented either with a gradual or a sharp onset. The results indicate that contrast sensitivity to a range of frequencies centered around 2–3 deg is decreased by a maximum of 0.3 log units when high frequency temporal stimulation induced ei...

Citations

... Since the early work by Ditchburn and Ginsborg (1952), Riggs et al. (1953), and Yarbus (1967), in which image fading with stabilization was demonstrated, the effects of FEM on spatial (Gilbert & Fender, 1969;Kelly, 1979a;Tulunay-Keesey & Bennis, 1979;Tulunay-Keesey & Jones, 1976;Watanabe, Mori, Nagata, & Hiwatashi, 1968) and spatiotemporal contrast sensitivity (Kelly, 1977;Kelly, 1979b;Kelly, 1981b), chromatic contrast sensitivity (Kelly, 1981a), detection of colored light (Ditchburn & Foley-Fisher, 1979), Vernier acuity (Tulunay-Keesey, 1960), edge, line, or overall form detection (Gerrits & Vendrik, 1970b;Gerrits & Vendrik, 1974; Tulunay-Keesey, 1960a), orientation discrimination (Rucci et al., 2007;Tulunay-Keesey, 1960), and retinal eccentricity (Gerrits, 1978) have been documented. Interestingly, there were large differences across studies in how much FEM affect perception. ...
... FEM is generally categorized into three major categories: drift (a low frequency, random walk), microsaccades (small, jerklike motions), and tremor (a high frequency, repeti-tive motion superimposed upon drift). 1 Early literature has shown that fixational eye motion helped to prevent the perception of a stationary image from fading away from view, by consistently providing a neural refresh. [2][3][4][5] In more recent studies, evidence suggests microsaccades have a much larger role in visual perception, modulating neural activity in cortical regions, enhancing the resolution of high spatial frequencies, and assisting in the neural processing of visual information. 4 Further, in clinical research studies, measures of FEM, specifically microsaccades, have been used as biomarkers for central nervous system disorders. ...
... For instance, although similar contrast sensitivity functions were obtained under normal viewing conditions, the contrast threshold elevation under stabilization ranged from zero (no effect at all) up to .10 times (1.0 log unit) across studies (Gilbert & Fender, 1969;Kelly, 1979a;Tulunay-Keesey & Bennis, 1979;Tulunay-Keesey & Jones, 1976;Watanabe et al., 1968). The differences in precision of retinal image stabilization (Gerrits, 1978) as well as the stimulus duration (Tulunay-Keesey & Jones, 1976;Tulunay-Keesey & Jones, 1980) have been identified as the primary determinants of these differences, and more precise stabilization and longer stimulus duration are associated with larger threshold elevation. ...
... ? Yes R: 4 2/1 R : 4 Nagy and Kamholz (1995) [ 50 Nicholas et al. (1996) [57] R: 3 3/1 2-3M 79% 0.0375 0.0375 Yes R: 6 2/1 R : 6 Olson et al. (1994) [58] ? 71% 0.2 a 0.1 a Yes T: 48 Polat and Sagi (1994) [60] T: 40 Rovamo et al. (1995 [66,67] ]3M 84% 0.1 0.1 Yes R: 8 Rovamo et al. (1996) [68] R: 8G 4/1 ]3G 84% 2 dB 1 dB No R: 10 2/1 R : 6 Sankeralli and Mullen (1996) [69] ? ...
... Brightness gradually declines to low residual levels called the Eigengrau or subjective gray (Gibson & Waddell, 1952;Gur 1989;Knau & Spillman, 1997). The characteristics of this fading have been extensively tested; it depends on the size of the field, background luminance and the amount of spatial information present (Olson, Tulunay-Keesey, & Saleh, 1993). Others have confirmed that spatial information, that is changes in luminance that give rise to contrast in an image, fades more quickly (Kelly, 1979) than brightness (Knau & Spillman, 1997). ...