Switch access scanning
Switch access scanning is an indirect selection technique (or access method), used by an assistive technology user, including those who use augmentative and alternative communication (AAC) to choose items from the selection set. Unlike direct selection (e.g., typing on a keyboard, touching a screen), a scanner can only make selections when the scanning indicator (or cursor) of the electronic device is on the desired choice. The scanning indicator moves through items by highlighting each item on the screen (i.e., visual scanning), or by announcing each item via voice output (i.e., auditory scanning), and then the user activates  a switch to select the item. The speed and pattern of scanning, as well as the way items are selected, are individualized to the physical, visual and cognitive capabilities of the user. While there may be different reasons for using scanning, the most common is a physical disability resulting in reduced motor control for direct selection. Communication during scanning is slower and less efficient than direct selection and scanning requires more cognitive skill (e.g., attention). Scanning using technology has an advantage allows the user to be independent in controlling the assistive technology for those with only one voluntary movement. Scanning  patterns. A scanning pattern refers to the way items in the selection set are presented to the user. It allows for easier item selection as the scanning is systematic and predictable. Three primary scanning patterns exist: Scanning control techniques. Scanning control and item selection occurs through switch activation in three general ways: