| Popis: |
The nature and role of long-term representations in the conduct of skilled movement were studied in the context of acquisition and operation of a typing skill based upon a newly designed two-hand chord typewriter. The system is composed of two, five-key panels, each independently capable of producing the full alphabet by using chord combinations to represent letters. Results from three experiments are reported. In the first, three different coding principles to map letters to chords on the two hands were experimented: Hand Symmetry, Spatial Arrangement, and unification of the two in a vertical posture. Coding rules had a pronounced influence on performance and their effect increased with training. Vertical representations were best, spatial arrangement second and hand symmetry the worst. A second experiment showed that the efficiency of vertical representations was not impaired when the panels were flattened down. In a third experiment, subjects were taught to imagine their panels as though they were tilted upright, and their performance improved. It is concluded that high-level representations have a mediating role in the conduct of skilled movement which does not diminish with practice. The human processing system appears to have an initial flexibility in the selection of a representation mode, but a commitment for a mode is made early in training and is likely to persist. A three-stage model of transcription is proposed. At the first stage, letters activate general schemas, followed by a conversion to the typing hand and specification of movement parameters on the second and third stages. |
