scotopic vision

vision that occurs in dim light by means of the retinal rod system. Because scotopic vision does not permit color discrimination, the visual scene appears in gray scale. However, the closer the illumination of a target is to 510 nm in wavelength, the brighter it will appear relative to other targets with the same energy, since this is the peak wavelength sensitivity for the rod system. Also called twilight vision. Compare photopic vision.

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Psychology term of the day

January 19th 2025

short-wavelength pigment

the photopigment present in one of the three populations of retinal cones that has maximum sensitivity to a wavelength of 419 nm. The absence of the gene for the short-wavelength pigment causes tritanopia, a form of color blindness in which blue and green are confused with one another. See also long-wavelength pigment; medium-wavelength pigment.