The elaboration of motor programs for the automation of letter production.

We investigated how children learn to write letters. Letter writing evolves from stroke-by-stroke to whole-letter programming. Children of ages 6 to 9 (N=98) wrote letters of varying complexity on a digitizer. At ages 6 and 7 movement duration, dysfluency and trajectory increased with stroke number. This indicates that the motor program they activated mainly coded information on stroke production. Stroke number affected the older children's production much less, suggesting that they programmed stroke chunks or the whole letter. The fact that movement duration and dysfluency decreased from ages 6 to 8, and remained stable at ages 8 and 9 suggests that automation of letter writing begins at age 8. Automation seems to require the elaboration of stroke chunks and/or letter-sized motor programs.