A comparison of contrast detection and discrimination

In order to complement previous studies of contrast detection, we have examined the effects of three stimulus variables (spatial frequency, retinal illuminance, retinal locus) and one visual disorder (amblyopia) on contrast discrimination. Although each factor has a profound effect on the detection of gratings on otherwise unpatterned displays, we find a similar dipper-shaped contrast discrimination function and similar supra-threshold Weber fractions for contrast under all these conditions.