How does a person with disabilities select the items to construct messages? It depends on the individual's abilities and preferences. No matter which method is used, it is crucial that the method work smoothly for the individual. Even the newest high tech device with all the bells and whistles will be useless if the individual cannot reliably construct the messages he or she needs to communicate.
Many AAC professionals and some AAC textbooks tend to describe access as either "direct selection" or "scanning." But, in my opinion, this approach is unnecessarily limiting to AAC users and their teams. According to Dowden and Cook, it's better to look at access with two broad categories: direct selection and indirect selection. Scanning, as mentioned above, is simply one of several indirect methods of access.
We will organize access methods around these two broad categories, with many subtypes within each one:
It is important that you understand that direct selection is always the preferred method of access whenever it is possible. It is always faster and more efficient than indirect selection methods.
You should also know that within the broad categories of direct and indirect selection, there are an infinite number of variations and modifications that improve access. Modifying a direct selection access or choosing an indirect selection method should always be done in conjunction with a motor specialist, an OT or a PT, who can assist in customizing the optimum selection technique for the individual.
Additional clinical considerations are beyond the scope of this website. These issues are covered better in a hands on AAC course, such as SPHSC 454 at the University of Washington.