Typewriting studies which compare novice and expert typists have suggested that highly trained typing skills involve cognitive process with an inner and outer loop, which regulate keystrokes and words, respectively. The present study investigates these loops longitudinally, using multi-level modeling of 1,091,707 keystroke latencies from 62 children (M age = 12.6yr.) following an online typing course. Using finger movement repetition as indicator of the inner loop and words typed as indicator of the outer loop, practicing keystroke latencies resulted in different developmental curves for each loop. Moreover, based on plateaus in the developmental curves, the inner loop seemed to require less practice to develop than the outer loop.
van den Bergh, J. M., Schmittmann, V. D., Hofman, A. D., & van der Maas, H. L. J. (2015). Tracing the development of typewriting skills in an adaptive e-learning environment. Perceptual and Motor Skills, 121(3), 727-745. https://doi.org/10.2466/23.25.PMS.121c26x6