Milestones of Hearing-Impaired Infants with Hearing-Impaired Parents

According to the American Speech-Language Hearing Association (http://www.asha.org/), over 30 children will be born in the US each day, and of these births, only about 5% are born to deaf parents.

Though deaf children with deaf parents are at a greater advantage of learning language than deaf children with typically hearing parents, once again, studies demonstrate that deaf children with deaf parents acquire language at a similar rate as typically hearing children with typically hearing parents. Deaf children are exposed to a sort of child-directed sign language by their parents in the early stages of their language acquisition, similar to the way in which typically developing children are exposed to child-directed speech. Child-directed signing includes using exaggerated facial expressions, shaping the child's hand to form a sign, and signing in the child's line of sight (Andrews, Logan, & Phelan, 2008). Hearing mothers can point to and name an object for their hearing children, but for deaf children linguistic input and nonverbal context occur in the same modality. Deaf mothers compensate for this by setting up “sight triangles” where they sign in within a triangle of the mother, child, and object they are referring to (Andrews, Logan, & Phelan, 2008). It is important to note that early deaf-mother with deaf-child interactions are shown to have positive effects on language development as well as social-emotional development (Schick, 10).

Outline of Sign Language Acquisition in Hearing-Impaired Children

The following is a general acquisition outline of how and when deaf children learn and use manual signs in ASL:

  • Onset
    • manual babbling
    • deaf children of deaf parents have actually demonstrated advantages in the onset of their first signs (8-11 months) in comparison to the onset of a hearing child's first words (12-13 months)
    • during the years in which a hearing-impaired child is acquiring language, they tend to make errors in ASL that parallel the mistakes that a hearing child will make with speech. However, for a deaf child these errors relate to the formational aspects of sign hand shape, location, and movement.
  • Content
    • noun signs
    • these are similar to first words, and phrases like “bye-bye”, “no”, and “sh!”
    • 12-15 months
  • Emotion signs
    • as early as 15 months (or within the first 100 signs), deaf children will begin to make signs corresponding to their physical states (i.e. sleepy, hungry, thirsty)
    • from about 18-20 months, signs may begin to correspond to feelings (i.e. sad, happy, angry)
    • this is the same in the language acquisition of typically-hearing children, but with spoken word rather than signed language
  • Cognitive verbs
    • from 18-30 or 36 months (at about 450+ signs), deaf children will begin to make signs for verbs like “want”, “like”, “think”, with “think” being the last to emerge
  • Negation
    • this overlaps with the development of cognitive verbs.
    • 18-24 months: “don't, want, none”
    • 24-30 months: “don't know, not-yet”
    • 30+ months: “can't, not”
  • Pronouns
    • 17-20 months (“me”, “you”)

The MacArthur Communicative Development Inventory

ASL exhibits both the grammatical complexity and organizational principles commonly seen in the spoken languages of the world. In order to learn more about the early lexical and grammatical development in deaf children born to deaf parents, the MacArthur Communicative Development Inventory was developed. Results from this inventory show that, on a whole, deaf children who are acquiring ASL in a natural environment develop sign language in a similar way to children who are learning spoken languages. The sequence and developmental timeline for signs for emotion, cognitive verbs, and wh-forms are very similar in comparison to those in English. (Anderson, 99).

In addition to providing more evidence on the typical language development in deaf children, the inventory also brought to light some noticeable differences in the development of language in deaf and hearing children.

  1. First, deaf children were producing signs at the first age sampled, which was 8 months. Children learning English generally do not produce their first words until 12 months old. This suggests that underlying cognitive abilities for language are in place earlier than thought, and it is the delayed development of speech mechanisms that causes the later development of language.
  2. Second, the data reveals that the vocabulary of the youngest children in the sample consists entirely of nouns, which is comparable to findings of hearing children learning English. However, the ASL children begin to demonstrate verbs earlier in their lexicon, which could be related to the structure of ASL, which often places verbs in the initial position of an utterance.

Check out What Does it all Mean to see how this compares to children who are developing spoken language and different factors that affect language acquisition.