ABSTRACT
This chapter considers Atypical Language Development. Von Tetzchner and Martinsen describe three broad categories of Augmentative and Alternative Communication (AAC) users: Expressive Language Group, Supportive Group, and Alternative Language Group. These three groups are likely to follow different trajectories in their acquisition of spoken language and AAC communication. Following are some of the differences a child may experience in atypical language acquisition: child's sensory-motor experience of the world; joint-attention and AAC; spoken language input; and vocabulary size, combining symbols and communicative functions. The optimal amount of spoken input is probably different for different children. Interventions such as Parent-Child Interaction may be helpful in establishing what is right for an individual child. In AAC acquisition, children are exposed to modelling from adults who are also just learning the AAC language themselves. Communication Matters, the UK charity for AAC, now has an AAC Evidence Base website. This includes theory-driven publications and practice-driven interventions, including single case studies.
