Table 1.
Time-courses for development of the major capacities of the speech motor system. The estimated amount of learning occurring in a neural system within a given time window is indicated as being Low, Medium, or High.
| Age and Development Stage | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Neural System | 0–1 mo. phonation | 2–3 mo. goo | 4–6 mo. expansion | 7–10 mo. canonical | 10–12 mo. Non-reduplicated | 1–2 yr. words | 3–5 yr. sentences | 6–18 yr. school | > 18 yr. mature |
| 1. Aud. state and error maps | Low | Low | Med | High | High | High | High | Med | Low |
| 2. Som. state and error maps | Low | Low | Med | High | High | High | High | Med | Low |
| 3. Aud.-motor transformations | Low | Low | Med | High | High | High | High | Med | Low |
| 4. Som.-motor transformations | Low | Low | Med | High | High | High | High | Med | Low |
| 5. Som.-aud. transformations | Low | Low | Med | High | High | High | High | Med | Low |
| 6. Speech sound map | Low | Med | High | High | High | Med | Low | ||
| 7. Aud. Target map | Low | Med | High | High | High | Med | Low | ||
| 8. Feedforward commands | Low | Med | High | High | High | Med | Low | ||
| 9. Som. target map | Low | Low | Med | High | High | Med | Low | ||
Abbreviations: Aud.=auditory; Som.=somatosensory.