Effect of Wavelength on Foveal Grating Acuity*

Acuity–luminance relations for a grating test object were determined with red, yellow, green, and blue narrow-band chromatic illuminants for five subjects.At intermediate and high luminance levels, acuities for blue were lower than for the other chromatic illuminants in four of the five subjects. One of these subjects also showed lower asymptotic acuity for red at high luminances. The fifth subject, who did not show lower blue acuity, exhibited lower asymptotic acuities than the other subjects. The low blue acuities observed in four of the five subjects are attributed to neural rather than dioptric factors.