Input Rate

The speed at which a user can produce individual keystrokes or character inputs, typically measured in seconds per keystroke. Input rate varies dramatically across access methods: touch typists may achieve 0.1-0.2 seconds per keystroke, while users of switch scanning systems or head pointers may require 1-3 seconds per keystroke. Understanding input rate is essential for AAC assessment because slower input rates amplify both the benefits of word prediction and the costs of scanning prediction lists. Systems should be evaluated at realistic input rates for the target user population.