When are Perceptual Qualities Psychological Kinds?

Psychophysics purports to measure and quantify variable qualities of our perceptual experience (color, heat, pitch, odor, etc.). In the early days of psychophysics, primitive perceptual qualities were determined by phenomenological analysis (e.g. hue, saturation, and lightness may introspectively be assessed as distinct qualities of color experience). Later, qualities were determined abductively as the best explanation for consistent behavior on psychophysical tasks (for instance "loudness" and "volume" were judged to be distinct qualities of auditory experience because subjects could consistently assign them independent values). Most recently, primitive perceptual qualities are determined by the mathematical transformation (via principle components analysis) or large data-sets of similarity judgments. These three criteria often diverge; furthermore, there is no guarantee that any of the three systematically track qualities of the physical stimuli used in psychophysical experiments. This talk will assess the different assumptions these methods make about the realism of perceptual qualities and, in particular, when we should treat a proposed set of perceptual qualities as legitimate psychological kinds.