1996 volume 25(10) pages 1203 – 1217

Cite as:
Howard I P, 1996, "Alhazen's neglected discoveries of visual phenomena" Perception 25(10) 1203 – 1217

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Alhazen's neglected discoveries of visual phenomena

Ian P Howard

Received 3 April 1995, in revised form 26 June 1996

Abstract. The first three books of the Book of Optics written by Alhazen in Cairo in the eleventh century were translated into English by A I Sabra in 1989. Book I deals with optics, the structure of the eye, image formation in the eye, and with the visual pathways. This book inspired all other books on optics from the thirteenth to the seventeenth century and formed the basis upon which Kepler solved the problem of image formation. However, Alhazen's work contained in Books II and III has been almost totally ignored. These two books contain an account of hundreds of observations and experiments carried out by Alhazen on a broad range of topics which are now studied under the heading of visual perception. He clearly enunciated many of the fundamental principles which are credited to scientists living in the past two hundred years, including a theory of unconcious inference; the law of equal innervation of the eye muscles; the principles of binocular direction; constancy of size, shape, and colour; induced visual motion; the vertical horopter; the fusional range of binocular disparity; and many others.

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