Using distinctive Fourier components to discriminate between complex patterns.
Observers discriminated between a plaid pattern formed by summing vertical and horizontal cosine gratings, and a plaid formed by multiplying the gratings. Such patterns are alike with respect to many non-Fourier primitives, but differ in the Fourier domain by diagonal components which are present in the plaid formed by multiplication, but not in the one formed by summing. When discrimination performance is related to the contrast of the diagonal components, it is found that the contrast threshold for discrimination is approximately the same as the threshold for detection of the isolated components. However, the psychometric function for discrimination is shallower than that for detection, suggesting the presence of masking. Despite the masking, the results support the proposition that discrimination processes may operate directly on the representations of local Fourier components.
Thomas
J P
JP
Psychology Department, University of California, Los Angeles 90024-1563.
Olzak
L A
LA
Shimozaki
S S
SS
D015350:Contrast Sensitivity / Q000502:physiology; D005583:Fourier Analysis; D006801:Humans; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011601:Psychophysics; D012684:Sensory Thresholds; D014793:Visual Cortex / Q000502:physiology