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ASL, however, likely takes a young child at least several years to master. Finally, the movement parameter of signs typically is initially produced by young children with intermediate accuracy. Some sign movements, such as making contact with one’s body or moving one’s hand back and forth, are produced accurately by very young signers. Other movements, or combinations of movements, may require many months or several years to master. In general, the number and complexity of sign movements increase considerably with age and growth in vocabulary size. Because young children often require many months or years before they learn to form various words or signs accurately, their caregivers early on will often accept incorrect pronunciations and respond to them fully. In some instances, the children’s sign or word productions will be identical formationally for concepts that would clearly be expressed differently in adult utterances. This is known as child homonymy. The phenomenon of child homonymy occurs when a young child uses a single phonetic form for two (or more) linguistic targets for which adults would use phonetically distinct forms. This phenomenon has long been recognized as being present in children learning to speak, although it is not clear whether it occurs because the child is not yet able to produce certain adult sounds or does not yet perceive them. More recently, child homonymy has been shown to occur in sign-learning children as well. That is, young sign-learning children also produce homonymous forms (a single manual form is used by a child to represent two or more adult target signs). Moreover, the incidence of homonymy in sign-learning children does not differ significantly from that reported for typically developing children learning to speak. The young sign-learning children’s highest incidence of sign homonymy, however, often takes place several months before the comparable peak incidence in the children learning to speak.