Small-field Tritanopia and the Effects of Voluntary Fixation

Abstract

Recently published wavelength discrimination curves for point sources have shown no tritanopic confusion of blue and green, and it has been suggested that this was because the observers scanned the field, instead of fixating on it. Curves measured by the author, also without fixation, but over a different range of field sizes and luminances, do show tritanopic confusion, although it is not as marked as in the older investigations. The curves also show that lowering the luminance, at a given field size, produces a different effect, and that discrimination between blue and violet, at 430 mμ, can be very good when fixation is avoided.