Categorical and coordinate relations in faces, or Fechner's law and face space instead?

Abstract

E. E. Cooper and T. J. Wojan (2000) applied the categorical-coordinate relations distinction to faces on the basis of a finding that two-eyes-up versus one-eye-up distortions had opposite effects in between-class (face normality) and within-class (face identity) tasks. However, Cooper and Wojan failed to match amount of metric change between their 2 deviation types and tested only 1 deviation level. In the present study, eyeheight was shifted (e.g., both eyes up or both eyes down vs. one eye up and one eye down) parametrically (11 levels) and normality and identity ratings obtained. There was no evidence of categorical changes in perception where these would have been predicted by Cooper and Wojan's theory. In all cases, the relationship between physical and perceived distortion followed Fechner's law. Differences across distortion types in Fechner threshold (the minimum deviation altering perceived normality or identity) are explained in terms of the variability associated with different dimensions in face space.