Apparent contrast of suprathreshold gratings varies with stimulus orientation

Abstract

Human contrast sensitivity is known to vary with both stimulus spatial frequency and orientation. Previous research has indicated, however, that the apparent contrast of a sinusoidal grating is independent of spatial frequency at suprathreshold levels. We have found that the apparent contrast of suprathreshold gratings is not independent of its orientation. Observers adjusted the apparent contrasts of vertical and oblique gratings to match a 40% standard. Contrast match deviations were found at a number of spatial frequencies, indicating a lack of contrast constancy with stimulus orientation. The apparent contrast of gratings in different orientations could not be predicted in any simple fashion from either contrast threshold differences or ratios.

Cognitive representation of linear motion: Possible direction and gravity effects in judged displacement

“…Perceptual research in a variety of settings has shown decrements in performance when stimuli are oriented at oblique angles (for review, see Appelle, 1972). For example, both resolution (Berkley, Kitterle, & Watkins, 1975;Bowker & Mandler, 1981) and vernier (Corwin, Moskowitz-Cook, & Green, 1977) acuity are impaired when the stimuli are oriented at angles intermediate to the horizontal and vertical axes. (3) Displacements in oblique directions might be smaller in magnitude than displacements in horizontal and vertical directions.…”

Variations in apparent spatial frequency with stimulus orientation: IL Matching data collected under normal and interferometric viewing conditions

“…Stimulus discrimination is likewise superior in the horizontal and vertical meridians (Bowker, 1980b;Matin & Drivas, 1979;Taylor, 1963). In addition, the apparent contrast (Bowker & Mandler, 1981) and length (Ritter, 1917;Thompson & Schiffman, 1974)of a stimulus depends on its orientation.…”

Monocular pattern alternation: Effects of mean luminance and contrast

“…There is virtually no effect of orientation at spatial frequencies at or below 4 cpd (see also Berkley, Kitterle, & Watkins, 1975). Nevertheless, other suprathreshold data have shown orientation effects in which it can be inferred that lateral interactions are weaker in the oblique orientations with large targets and at medium spatial frequencies (Bowker & Mandler, 1981;Kitterle, 1973). In addition, other research (Kitterle & Thomas, 1980) indicates that at higher spatial frequencies the effect of orientation on alternation rate is not found.…”