Kimball, Robert H.  "The Incoherence of Whitehead's Theory of Perception."  Process Studies 9, nos. 3-4 (Fall-Winter 1979): 94-104.

Abstract

Whitehead develops a theory of perception in Process and Reality which attempts to overcome traditional Cartesian dualities by integrating a causal explanation of perception with a description of its uninferred contents.  This attempt does not succeed and is fundamentally misguided, since the unification of representational and direct theories of perception which it entails is incoherent.  Direct realism renders mediated perception unnecessary, and mediated perception makes realism impossible.  [Abstract from The Philosopher's Index]