The role of accommodation in the control of binocular rivalry

Abstract

The role of accommodation in the control of binocular rivalry (BR) has been granted various degrees of importance by Es in the past. The most recent investigation by Fry (1936) concluded that accommodation provides the basis of BR control through the blurring of retinal images. However, the present study found that the introduction of very small artificial pupils (0.5 mm) did not reduce BR control. It was concluded that if accommodation changes are occurring with large pupils, the resulting image blurring plays no part in control of rivalry. Experiment 2 tested the effect of paralyzed intrinsic eye muscles and found almost the same degree of control as in the normal state. The slight decrease of control that was present was attributed to a general performance decrement, since slight performance decrements with eye paralysis were also found in a visual reaction-time task and hand dynamometer test. In Experiment 3, it was found that the increased control that was obtained over several practice sessions was mostly retained during subsequent eye paralysis. These findings and, in addition, a very significant control of rivaling afterimage stimuli under eye paralysis strongly suggest a central component of BR control rather than one based on accommodation. © 1971 Psychonomic Journals, Inc.