The Titchener illusion makes a circle surrounded by other circles appear smaller if the surrounding circles
are enlarged. This effect is especially striking when comparing the cases where the
surrounding circles are respectively smaller and larger
than the middle circle, as in the illustration above in
which the red circles are exactly the same size. The arrangement
appears in Titchener (1901, p. 169).
National Science and Technology Centre, Australia. "Titchener Illusion Explanation." http://www.questacon.edu.au/html/titchener_illusion_explanation.html.Titchener,
E. B. Experimental Psychology: A Manual of Laboratory Practice, Vol. I, Part
1. New York: Macmillan, p. 169, 1901.
