The oculomotor system remains plastic so that it can maintain clear single binocular vision during development and also in novel visual conditions (such as wearing new spectacles). It is important to understand this adaptation process so that we can predict in advance potential problems that might arise with new optical devices such as virtual reality head mounted displays. In this paper we present neural network models of adaptation to vertical disparities at different points in the visual field and argue that regularization (weight decay) provides a more realistic account of the empirical data than other approaches.

We measured the ability to fuse dichoptic images of a horizontal line alone or in the presence of a textured background with different vertical disparity. Nonius-line measurements of vertical vergence were also obtained. Diplopia thresholds and vertical vergence gains were much higher in response to an isolated vertically disparate line than to one with a zero vertical-disparity background. The effect of the background was maximum when it was coplanar with the target and decreased with increasing relative horizontal disparity. We conclude that vertical disparities are integrated over a restricted range of horizontal disparities to drive vertical vergence. 2000 Elsevier Science Ltd. All rights reserved.

In order to maintain clear, single binocular vision developmentally and in different visual environments, it is necessary for the oculomotor system to be plastic. During development, plasticity is required to compensate for changes in the size of the eyeball and the distance between the eyes. Adults also show plasticity when wearing optical devices (such as spectacle lenses and head mounted displays) which require local adaptation of the oculomotor system. It is therefore of interest to study the details of this plasticity since it will have consequences for the types of optical devices that can be used with comfort and safety. We have begun this study by simulating the human adaptive response to vertical disparities at different points in the visual field, and using comparisons with empirical data to explore the possible biological limitations of this adaptation process. 1