Dual scaling law in human area perception of concentric circles

Abstract

Understanding how humans perceive objects may unravel psychophysical laws that allow us to gain mastery of issues involving various cognitive phenomena. Here, we conduct an area-space task using circle as precept. We show that when the stimuli are smaller than the reference area A of the circle, individuals tend to underestimate the perceived area. On the other hand, overestimation is observed for the regime where the stimuli are greater than A. The psychophysical relationship between the perceived area and the stimulus is obtained and shown to obey Stevens’ law. However, contrary to prevalent idea that a single diagnostic Stevens’ exponent (γ) exists for every psychophysical phenomenon, our results indicate conclusively scale duality. For stimuli less than A, γ = 1.1 while, for stimuli greater than A, γ = 1.7. The existence of two scaling exponents in a single psychophysical experiment is a new finding that can alter existing statistical approaches in the treatment of human perception.