Scanning

An indirect selection method used in augmentative and alternative communication (AAC) and assistive technology where items (letters, words, or commands) are highlighted sequentially by the system, and the user activates a switch to select the currently highlighted item. In row-column scanning, rows are highlighted first; when the user selects a row, individual items within it are then highlighted one by one. Scanning enables text entry and device control for users who can only operate one or two switches, though it is inherently slower than direct selection methods. The speed and usability of scanning depend heavily on the dwell time (how long each item is highlighted), the layout of items, and the predictability of the scanning pattern.