We systematically analyse the binocular disparity field under various
eye, head and stimulus positions and orientations. From the literature
we know that certain classes of disparity which involve the entire di
sparity field (such as those caused by horizontal lateral shift, diffe
rential rotation, horizontal scale and horizontal shear between the en
tire half-images of a stereogram) lead to relatively poor depth percep
tion in the case of limited observation periods. These classes of disp
arity are found to be similar to the classes of disparities which are
brought about by eye and head movements. Our analysis supports the sug
gestion that binocular depth perception is based primarily (for the fi
rst few hundred milliseconds) on classes of disparity that do not chan
ge as a result of ego-movement. Copyright (C) 1996 Elsevier Science Lt
d.