Message Reception and Message Uncertainty

Abstract

A basic principle of language engineering is that the accuracy of message reception in noise is determined by the number of alternative messages that might be communicated. However, it is not clear whether the number of alternative messages available for presentation or the number of possible message-responses is the critical determinant of performance. We attempted to resolve this question in experiments in which trained listeners first memorized various sets of n spondee words (n varied from 2 to 64). Words, chosen at random from the set of n words, were then read, one at a time, over a noisy communications channel. Shortly after the word was read, the listener was instructed that the presented word was one of k possible words, where k⩽n. Accuracy of message-reception was found to be practically independent of the size of the message class (n), for a constant number of possible response alternatives (k). Furthermore, the number of necessary response distinctions—rather than response-uncertainty per se—appears to be the critical determinant of accuracy of communications.