Empirical examination of cooperation, effort and risk in task-oriented dialogue

This thesis presents a discussion of proposed structuring principles for dialogue, and tests them empirically using data from the HCRC Map Task Corpus. The concepts of Cooperation (as described by Grice, and as used more generally in Linguistics), Coordination, Collaboration, Parsimony, Risk and Effort are ex¬ amined, and empirically testable hypotheses are developed, with which we are able to evaluate the claims for these principles in the context of task-oriented dialogue. In order to test our hypotheses, we categorise the utterances in our database in terms of Risk and Effort. Unlike Discourse Analysis, Conversation Analysis or Dialogue Games, our approach is evaluative. The intent in our dialogue coding is not only to label what the speakers did, but also to assess it in terms of its appropriateness at that point in the dialogue: the system codes not only what people do, but also what they don't do. Therefore, our system marks both the presence and absence of dialogue attributes. The hypotheses derived from the structuring concepts were statistically tested on the data produced by the coding system. The results produced by the empiri¬ cal tests showed a relationship between dialogue errors and task errors, but not between increased effort and increased task success. The importance of matched effort was also demonstrated, as dialogue pairs who invested similar amounts of effort produced better task results. Dialogue pairs also produced better results over time, which we argue is due to the focusing of effort. Participants work out where their effort should be channelled so that they can increase risk-taking where problems have not occurred, and decrease risk-taking where problems have occurred. These results suggest that interactants' behaviour follows a Principle of Least Individual Effort, which we argue subsumes the Principle of Parsimony and thus the Risk-Effort Trade-Olf. We reject the Principle of Least Collaborative Effort because although the empirical result of high effort not being associated with task success supports this principle in theory, we argue that its motivation is not supported in practice. The empirical work also distinguishes between what we term 'Gricean Coop¬ eration', and folklinguistic notions of Cooperation found in the literature. In general terms, Gricean Cooperation predicted the same type of effort-minimising behaviour as the Principle of Least Individual Effort, and was thus supported by the empirical work. However, the concept of 'helpfulness' suggested by more general uses of Cooperation made predictions which were in conflict with those of the Principle of Least Individual Effort, and were found not to be supported