ABSTRACT
In the previous chapter I described three types of measurement that converged on a common picture of “contrast brightness.” This was a single bipolar dimension that included the brightness of increments and the darkness (or lightness) of decrements. Contrast brightness was primarily determined by the physical contrast of test light and surround. I argued that it reflected retinal contrast coding. All three types of measurement—matching, scaling, and discriminating—were made in severely restricted situations. One restriction in particular will repeatedly concern us in this chapter: The patches to be matched, scaled, or discriminated either were, or appeared to be, seen against a common background. It was under that condition that brightness was determined by contrast.
