Comparing Visual and Spoken Language Disorders: Similarities and Differences
A unique characteristic of signed language could pose problems for some children. The processing of signed languages requires visual-spatial perspective taking. A signer can describe a scene by creating a small-scale map with certain hand shapes and movements placed in strategic locations in front of their body. The viewer, who is normally positioned opposite the signer, often interprets the scene by taking on the perspective of the signer. If a deaf child who uses signed language for primary communication were to struggle with visual perspective-taking, that child could confuse the locations of people or objects that are described in a signed scene. In this case, a cognitive deficit (weak visual spatial skills) co-occurs with a linguistic deficit for the deaf child. A hearing/speaking child who exhibits weaknesses with visual perspective taking might not demonstrate impaired language since spoken language seemingly relies less on visual spatial skills; that child might struggle with providing directions via language, but it is debatable whether such a cognitive weakness might result in a language impairment. Details of a case study will be presented, which describes this type of deficit for a deaf/signing child.
Young users could also benefit from a characteristic of signed languages: the rate at which linguistic units are communicated in that modality. Every second of speech a speaker utters multiple syllables and meaningful units. In sign, the rates at which syllables and meaningful units are produced is also rapid, but to a lesser degree, and sequences of units are notably different. Information appears simultaneously (via the hands, face, and torso), and words are composed of short sequences of syllables. These differences across speech and sign, among others, yield different results with atypically developing children who struggle with aspects of language. In particular, deaf/signing children (as showcased by 43 subjects in a group study) identified as atypically developing do not struggle with identifying and responding to target words in signed sentences that are presented at normal and fast rates, whereas hearing/speaking children do.
This research suggests that signed languages can be both challenging and beneficial to the young learner.