In peripheral vision, a letter that is easily recognized on its own becomes unrecognizable if surrounded by other letters. This “crowding” phenomenon (Stuart & Burian,
1962) has been discussed scientifically for some 60 years but is only beginning to be understood (for review, see Pelli, Palomares, & Majaj,
2004; Strasburger,
2003). Crowding in the amblyopic fovea was first reported by Irvine (
1945), “single letters or the direction of … an E could be identified by the amblyopic eye, if viewed one letter at a time, but when placed in conjunction with other letters in a line, confusion affected the interpretation”. At about the same time, the ophthalmologist Hermann Burian noted that his orthoptist recorded better visual acuities in amblyopic patients than he did. The orthoptist used isolated letters to measure acuity, whereas he used letters arranged in a row (Burian & von Noorden,
1974). The phenomenon of crowding in amblyopia has been repeatedly confirmed (Bonneh, Sagi, & Polat,
2004; Flom, Weymouth, & Kahneman,
1963; Hariharan, Levi, & Klein,
2005; Hess, Dakin, Tewfik, & Brown,
2001; Hess & Jacobs,
1979; Levi & Klein,
1985; Levi, Hariharan, & Klein,
2002a; Stuart & Burian,
1962). Interest in crowding is growing quickly, with many recent publications, including this special issue of the
Journal of Vision.