Contrast sensitivity for vertically and obliquely oriented gratings as a function of grating area

Contrast sensitivity for both vertically and obliquely oriented gratings increased with increases in stimulus area to an asymptotic value. Sensitivity grew more slowly for oblique gratings and reached an asymptotic value at a larger area than for vertical gratings. For equal areas, oblique gratings always yielded poorer sensitivity. The results suggest a larger spatial summation area for obliquely oriented gratings.