Role of Changes in Accommodation and Convergence in the Perception of Size*

This is the authors' abstract. We don't add key points for this paper.

The effect on perceived size of changes in accommodation and convergence was determined at various observation distances. Accommodation and convergence were varied by lenses and prisms chosen so as to preserve the normal relationship between these two functions for all conditions of observation. For observation distances up to about one meter, perceived size is proportional to the distance at which the accommodation and convergence in force would normally obtain. At greater distances, this relationship becomes progressively less marked. It is concluded that accommodation and convergence could mediate size constancy only at observation distances of one meter or less, and that other mechanisms must be operative at greater distances of observation.