Augmentative and alternative communication: past, present and future.

Augmentative and alternative communication (AAC) for severely communicationally impaired people has developed with input from clinicians, users and their families, manufacturers, and researchers. A number of users of AAC are now internationally known figures. The increasing power and decreasing size and cost of computer-based technology continually offer new possibilities for improving AAC systems. It is important that such systems take into account the real needs of users, and the complex nature of human communication. It is also important to realize that AAC development is not a technical question alone. Many effective techniques do not involve sophisticated technology, and the provision of AAC for those who need it is often a matter of policy implementation rather than technical development. AAC is a new and exciting field. It is one which offers many challenges to all those associated with it. The benefits, however, are enormous. In order to advance the field increased international co-operation is required with respect to interventions, technologies, policies and services.