Yz. Wang et al., INTERACTION BETWEEN SUB-NYQUIST AND SUPRA-NYQUIST SPATIAL-FREQUENCIESIN PERIPHERAL-VISION, Vision research, 37(18), 1997, pp. 2545-2552
In peripheral vision, high-frequency gratings beyond the Nyquist limit
are visible as aliased patterns but, as shown previously, their visib
ility can be masked by superimposed sub-Nyquist gratings, Is the conve
rse also true? Can supra-Nyquist gratings affect the detectability of
sub-Nyquist gratings? In this study, we investigated the masking effec
t of high contrast, supra-Nyquist components of a compound grating on
the contrast detection of sub-Nyquist components by employing a tempor
al three-alternative, forced-choice (3AFC) masking paradigm, We found
that high-frequency, aliased gratings with contrast just 2 or 3 times
above threshold can have a powerful masking effect on low-frequency, r
esolved gratings in peripheral vision, This result was surprising beca
use prior results from sub-Nyquist masking studies in the fovea and th
e periphery have indicated that masking occurs only when the mask cont
rast is at least 5 times greater than threshold, Strong masking by sup
ra-Nyquist gratings that are only just visible may be accounted for by
an irregular sampling model in which the alias of the mask is distrib
uted over a band of frequencies in the sub-Nyquist range, Furthermore,
if undersampling is the explanation for the results of this study, th
en masking must occur after spatial sampling, (C) 1997 Elsevier Scienc
e Ltd.