Abstract
This study evaluated the performance of a lexical prediction communication program. It showed that lexical prediction saves key/switch activation effort by as much as 50% compared to normal typing. For individuals with significant motor disabilities, the technique may also save on the time required to prepare a message. On the other hand, use by individuals who have significant perceptual deficits may result in an increase in the time required to prepare a message. The study also developed a procedure and a set of indices that may be used to compute quantitative measures of performance of assistive communication devices. The procedure yields a composite performance index that may be useful for “rough and ready” comparison among various AAC devices and techniques. The procedure is especially useful for comparative studies of communication acceleration techniques.