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Brazilian Journal of Medical and Biological Research

versión impresa ISSN 0100-879Xversión On-line ISSN 1414-431X


Contrast sensitivity to angular frequency stimuli is higher than that for sinewave gratings in the respective middle range. Braz J Med Biol Res [online]. 1997, vol.30, n.5, pp.633-636. ISSN 0100-879X.

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 J0 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 J0 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

Palabras clave : spatial frequency; CSF; J0 targets; angular frequency; contrast sensitivity; contrast thresholds.

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