duplicate the route. The HCRC Dialogue Database [3] We hypothesise that agents who engage in task- contains 128 such dialogues; in this work we examined oriented dialogue usually try to complete the task with eight plus a set of dialogues from the pilot study used the least effort which will produce a satisfactory so- in Shadbolt's work [17]. Agents who wish to avoid plan lution. Our analysis of a corpus of map navigation task dialogues shows that there are a number of different aspects of dialogue for which agents can choose either to expend extra effort when they produce their initial utterances, or to take the risk that they will have to recover from a failure in the dialogue. Some of these decisions and the strategies which agents use to recover from failures due to high risk choices are simulated in the JAM system. The human agents of the corpus purposely risk failure because this is generally the most efficient behaviour. Incorporating the same behaviour in the JAM system pr...