Word Prediction and Communication Rate in AAC

Word prediction systems can reduce the number of keystrokes required to form a message in a letter-based AAC system. It has been questioned however, whether such savings translate into an enhanced communication rate due to the additional cognitive load (e.g., shifting of focus and scanning of a prediction list) required in using such a system. Our hypothesis is that word prediction has great potential in enhancing communication rate, but the amount is dependent on the accuracy of the word prediction system. Due to significant user interface variations in AAC systems and significant differences between communication rates achieved by different users on even the same device, this hypothesis is difficult to verify. We present a study of communication rate and word prediction systems using “pseudo-impaired” participants and two different word prediction systems compared against letter-by-letter entry. We find that word prediction systems can in fact speed communication rate, and that a more accurate word prediction system can raise communication rate higher than is explained by the additional accuracy of the system alone.