In the present review, we argue that the perceptual system has developed functionally specialized skills for letter perception through extensive reading experiences, thereby leading to optimal reading behavior. Reading experiences provide the skill to efficiently detect individual letters in a string without interfering with spatially neighboring ones. Through reading experiences, children acquire the skill to perceive letters analytically rather than holistically. Despite accumulating reading experiences, letters are constantly categorized at a basic level. Through reading experiences, the skills to adapt to font and orientation regularities of letters in a text are acquired. Furthermore, these experiences foster the skill to temporarily inhibit the active visual code of a recently perceived letter and thereby protect currently progressing letter processing from interfering with temporally neighboring letters. Functionally specialized skills of letter perception are built into the perceptual system and contribute to automaticity in fluent reading. The functional specialization of letter perception can be regarded as a manifestation of perceptual learning that adapts to properties of the external environment unique to reading and follows internal rules regarding reading behavior.
