Could Optical ‘Pushes’ Be Inertial Forces? A Geometro-Dynamical Hypothesis

Abstract

Under various circumstances perceived optical disturbances have been shown to upset an observer’s upright posture (e.g., Lee’s gliding room), but no principled explanation has yet been proposed that will handle these phenomena. These so-called optical ‘pushes’ are conveyed by kinematic information but they act on the observer as if they were kinetic forces. Information (geometry and time) and forces (geometry, time, and mass) thus are mismatched in dimensionality—a problem which precludes treating optical pushes explicitly as mathematical functions. Interpreting such apparent forces as cognitive representations of real forces merely exacerbates the problem. Instead an argument is presented that agrees more with ecological psychology’s view that such ‘forces’ must be directly perceived. Specifically, d’Alembert’s Principle adopted from classical mechanics provides a way to construe information for optical pushes as functionally equivalent to inertial forces that arise in reaction to impressed forces and thereby resolve the dimensional mismatch problem. Several examples are given to illustrate this approach.