Rehabilitation of a classical notion of Panum's fusional area.
It is argued that (1) the work of Burt and Julesz does not challenge the classical notion of Panum's fusional area; (2) their disparity gradient concept is contradicted by some of their own findings as well as by those of Krol and van de Grind; (3) their results can be accounted for by the classical concept of Panum's fusional area if eye vergence is taken into account; (4) the explanations suggested by Burt and Julesz for the depth perception aspects of Panum's limiting case and the double-nail illusion are based on unwarranted generalisation of results concerning binocular direction vision.
D003867:Depth Perception; D004193:Discrimination Learning; D004292:Dominance, Cerebral; D005556:Form Perception; D006801:Humans; D009903:Optical Illusions; D011601:Psychophysics