The classification of inputs — printed characters, spoken words, shapes — the basic problem any sensing cybernetic system must solve.
Young gives two full chapters to it, from Flower's 1916 reading typewriter and photocell arrays to the Voder and Vocoder speech machines, while puncturing some of the hype.
George names pattern recognition as the basic problem of input — perceiving and recognising objects, processes and events — for any rational information processor.