ALHAZAN

(c. 965-1040)

Alhazan, whose real name was Abu Ali al-Hasan ibn al-Haytham, is also known under the names al-Basra (from Basra, in what is now Iraq), and al-Misri (from Egypt). He was an Arab mathematician, who has been credited with providing the earliest known classification of *illusions. In his work on optics Alhazan focuses primarily on *physical illusions such as reflections from curved surfaces and atmospheric refraction, but he also draws attention to the part played by knowledge and inference in the mediation of illusions.

Sabra, A.I. (1989).The optics of Ibn Al-Haytham. 2 Volumes. London: Warburg Institute. Gregory, R.L. (1991). Putting illusions in their place.Perception, 20, 1—4.