Between 8 and 12 months, babies may stumble on words like "mama" and "dada" accidentally, learning what they mean when they see the reaction from their caregivers. They may repeat "mama" and "dada" throughout the day to practice uttering the new sounds, but will soon begin using these words to attract the attention of their parents. Eventually, they will use these words only when they want to communicate their meanings.
References
- Shelov, S. P. (Editor-in-Chief). (2004). Caring for Your Baby and Young Child: Birth to Age 5. The American Association of Pediatrics. Revised edition. New York: Bantam Books.