Adaptation to prisms: change in internally registered eye-position.

It was shown that subjects who inspected immobile parts of their own body through ophthalmic prisms subsequently pointed incorrectly towards visual targets with both hands, i.e. they pointed as if signals derived from the system responsible for positioning the eye had been changed by a constant. It was further shown by a direct method that the subjects' appreciation of eye-position had indeed undergone a change as a result of such inspection, and that it was of an order great enough to explain the observed changes in pointing behaviour.