Boundary-curve slope in a categorical loudness function encodes perceptual category certainty

Evidence

In each MCPF, the vertical distance between the upper and lower boundary curves for a category is the probability of that category. The steeper the slope of a curve, the more defined the distinction between categories, whereas shallower curves coincide with probability being more distributed across categories, over a range of levels. A wider probability distribution across categories indicates that the listener had more uncertainty (i.e. entropy) in their responses. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2549

Categorization

• DEFINE: Defines how the multi-category psychometric function is read: slope of category boundary curves = listener certainty, vertical distance between curves = category probability.