The neural representation of visual space

Vernier acuity, crowding and cortical magnification

“…It is of special interest to attempt to relate the decline in visual performance with eccentricity to changes in the anatomy and physiology of the visual system (Weymouth, 1958;Cowey and Rolls, 1974;Rovamo et al, 1978;Koenderink et al 1978;Drasdo, 1977;Virsu and Rovamo, 1979;Schwartz 1980Schwartz , 1983. Our results, in agreement with Westheimer (1982) show that vernier acuity falls off faster with eccentricity than does grating acuity.…”

Peripheral positional acuity: Retinal and cortical constraints on 2-dot separation discrimination under photopic and scotopic conditions

“…For tasks which scale with eccentricity, there is often a striking resemblance between the rates of change of the behavioural thresholds and the morphology of either the retina or primary visual cortex. The variation of human resolution and contrast sensitivity within the central 10 deg parallels that of human and monkey cone spacing (Rolls & Cowey, 1970;Thibos, Cheney & Walsh, 1987;and Williams & Coletta, 1987), ganglion cell separationz (Weymouth, 1958;Rolls & Cowey, 1970;Drasdo, 1977;Rovamo, Virsu & Nasanen, 1978;Levi, Klein & Aitsebaomo, 1985;and Schein, 1987) receptive field size (Dow, Snyder & Bauer, 1981). The precision of bisecting the space between two features also scales to a single factor for a wide range of feature-separations , although its scaling factor is comparable to current estimates of the monkey Vl cortical magnification factor (Dow et al, 1981;Tootell, Silverman, Switkes & De Valois, 1982;and Van Essen, Newsome & Maunsell, 1984) which falls off three to four times faster than contrast sensitivity and resolution .…”

The sensitivity of the peripheral visual system to amplitude-modulation and frequency-modulation of sine-wave patterns

“…This view was first established for visual acuity: acuity is dire&y proportional to ~tf (Cowey and Rotls, 1974;Drasdo. 1977, Koenderink ef rrl., 1978a.…”