Independent component analysis reveals transient component of divergence varies with initial position

Vergence eye movements allow humans to view images in depth by turning the eyes inward (convergence) or outward (divergence). Four subjects were studied and tracked four degree disparity steps at different initial positions. This study shows that convergence and divergence dynamics differ depending on initial vergence position. The velocity of divergence increases for initially near targets, while convergence responses are similar irrespective of the initial position. It is speculated that the difference observed in divergence is a result of difference in magnitude of the fusion initiating component (transient component). Preliminary data using independent component analysis (ICA) shows the divergence system contains a step (sustained) component and pulse (transient) component where the amplitude of the pulse is dependent on the initial stimulus position.