Contrast sensitivity to angular frequency stimuli is higher than that for sinewave gratings in the respective middle range
Braz. j. med. biol. res
;
30(5): 633-6, May 1997. ilus
Article
in English
| LILACS
| ID: lil-196675
ABSTRACT
This study compares contrast thresholds for sinewave gratings, or spatial frequencies (1/CSF) with contrast thresholds for angular frequencies (1/aCSF) and for radial frequencies, or J(0) targets (1/rCSF). Observers had to differentiate between one of these frequency stimuli and a stimulus at mean luminance within a forced-choice procedure. All measurements were made with the same equipment, methods and subjects. Our results show higher sensitivity to, or lower thresholds for, angular frequencies when compared to either sinewave gratings or J(0) targets. Contrast values in arbitrary units, in the lower threshold range for angular frequencies, were about half those required to differentiate sinewave gratings from mean luminance in its most sensitive range.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Photic Stimulation
/
Vision, Ocular
/
Visual Perception
/
Contrast Sensitivity
Type of study:
Diagnostic study
Limits:
Humans
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
1997
Type:
Article
/
Project document
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