“Studies on the Telegraphic Language: The Acquisition of a Hierarchy of Habits”, 1899 (; backlinks; similar):
Investigated the different stages involved in learning telegraphy. One S was tested each week on: (1) rate of receiving letters not making words, (2) rate of receiving letters making words, but not sentences, and (3) rate of receiving letters making words and sentences.
Results indicate that a hierarchy of psycho-physical habits were required to receive the telegraphic language. From an early period, letter, word and higher habits made gains together, but not equally. No plateau appeared between the learning of letters and words; the first one occurred after the learning of words. Later, there was a second ascent, representing the acquisition of higher language habits.
Effective speed was largely dependent upon the mastery of these habits, which led to greater accuracy in detail.
Concluded that the rate of progress depended partly on the rate of mental and nervous processes, but far more on how much was included in each process.