Linguistic analysis of natural language communication with computers

Interaction with computers in natural language requires a language that is flexible and suited to the task. This study of natural dialogue was undertaken to reveal those characteristics which can make computer English more natural. Experiments were made in three modes of communication: face-to-face, terminal-to-terminal and human-to-computer, involving over 80 subjects, over 80,000 words and over 50 hours. They showed some striking similarities, especially in sentence length and proportion of words in sentences. The three modes also share the use of fragments, typical of dialogue. Detailed statistical analysis and comparisons are given. The nature and relative frequency of fragments, which have been classified into twelve categories, is shown in all modes. Special characteristics of the face-to-face mode are due largely to these fragments (which include phatics employed to keep the channel of communication open). Special characteristics of the computational mode include other fragments, namely definitions, which are absent from other modes. Inclusion of fragments in computational grammar is considered a major factor in improving computer naturalness. The majority of experiments involved a real life task of loading Navy cargo ships. The peculiarities of face-to-face mode were similar in this task to results of earlier experiments involving another task. It was found that in task oriented situations the syntax of interactions is influenced in all modes by this context in the direction of simplification, resulting in short sentences (about 7 words long). Users seek to maximize efficiency In solving the problem. When given a chance, in the computational mode, to utilize special devices facilitating the solution of the problem, they all resort to them. Analyses of the special characteristics of the computational mode, including the analysis of the subjects" errors, provide guidance for the improvement of the habitability of such systems. The availability of the REL System, a high performance natural language system, made the experiments possible and meaningful. The indicated improvements in habitability are now being embodied in the POL (Problem Oriented Language) System, a successor to REL