GVU Technical Report Number:
GIT-GVU-94-24
Title:
A Labeled Lines Explanation of the Perceived Spatial Frequency of
Moderate-Near-Threshold- and Zero-Contrast Spatial Patterns
Authors:
Elizabeth T. Davis
Dean Yager
Robert A. King
B. Arthur Kirkland
Abstract:
We tested the predictions of a multiple-channels model about the
appearance of spatial patterns. Specifically, we tested how encoding the
perceived spatial frequency of a near-threshold pattern compared to the
encoding of a zero-contrast or moderate-contrast pattern. For example,
the model predicts that a near-threshold pattern's mean perceived spatial
frequency is a weighted average of the response to the stimulus and the
noise. Six subjects used the method of adjustment procedure to match a
peripherally-viewed test stimulus (or a blank) with a foveally-viewed
grating. For near-threshold patterns we found a smooth perceived spatial
frequency function, with a smaller range of perceived spatial frequencies
than obtained for 0.16 contrast patterns. These results are consistent
with the model's predictions: noise can affect the appearance of
near-threshold and zero-contrast patterns.
Keywords:
Labeled lines, perceived spatial frequency, spatial-frequency channels,
noise, Signal Detection Theory
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