Abstract

Recently we reported that hyperacuity thresholds for separation-discrimination tasks were not smooth functions of spatial variables but rather were regularly segmented with sharp transitions between the segments.1 In this study we have measured the orientation dependence of two tasks involving visual hyperacuity, the discrimination of spatial frequencies and the discrimination of vernier offsets, in the vicinity of a transition between segments. The orientation dependence of both tasks contains a periodic component with a period of 60°. We interpret this as evidence that the cortical substrate that processes spatial information has a hexagonal two-dimensional organization, preserving the hexagonal packing of the foveal photoreceptors.

© 1984 Optical Society of America

Spatial-frequency discrimination at low frequencies: evidence for position quantization by receptive fields

Joy Hirsch and Ron Hylton
J. Opt. Soc. Am. A 2(2) 128-135 (1985)

Physical limits of acuity and hyperacuity

Wilson S. Geisler
J. Opt. Soc. Am. A 1(7) 775-782 (1984)

Cortical magnification and peripheral vision

Veijo Virsu, Risto Näsänen, and Kari Osmoviita
J. Opt. Soc. Am. A 4(8) 1568-1578 (1987)

Evidence for positional coding in hyperacuity

M. J. Morgan, R. M. Ward, and G. J. Hole
J. Opt. Soc. Am. A 7(2) 297-304 (1990)

Spatial-frequency model for hyperacuity

C. R. Carlson and R. W. Klopfenstein
J. Opt. Soc. Am. A 2(10) 1747-1751 (1985)