Access to AAC: present, past, and future.

Historically, access in augmentative and alternative communication (AAC) has been conceptualized as the physical operation of AAC technologies; more recently, research and development in the cognitive and social sciences has helped to broaden the concept to include a range of human factors involved in the successful use of AAC technologies in social interactions. The goal of this article is to expand the current understanding of communication access by providing a conceptual framework for examining AAC access, evaluating recent scientific and technical advances in the areas of AAC, and discussing the challenges to accessing AAC technologies for a range of communication activities.