Cortical Dynamics and Awareness State: An Interpretation of Observed Interstimulus Interval Dependence in Apparent Motion

Abstract

In a recent paper on Cortical Dynamics, Francis and Grossberg raise the question how visual forms and motion information are integrated to generate a coherent percept of moving forms? In their investigation of illusory contours (which are, like Kanizsa squares, mental constructs rather than stimuli on the retina) they quantify the subjective impression of apparent motion between illusory contours that are formed by two subsequent stimuli with delay times of about 0.2 second (called the interstimulus interval ISI). The impression of apparent motion is due to a back referral of a later experience to an earlier time in the conscious representation. A model is developed which describes the state of awareness in the observer in terms of a time dependent Schroedinger equation to which a second order time derivative is added. This addition requires as boundary conditions the values of the solution both at the beginning and after the process. Satisfactory quantitative agreement is found between the results of the model and the experimental results. We recall that in the von Neumann interpretation of the collapse of the quantum mechanical wave-function, the collapse was associated with an observer's awareness. Some questions of causality and determinism that arise from later-time boundary conditions are touched upon.