Abstract: End-to-end task-oriented dialog models have achieved promising performance on collaborative tasks where users willingly coordinate with the system to complete a given task. While in non-collaborative settings, for example, negotiation and persuasion, users and systems do not share a common goal. As a result, compared to collaborate tasks, people use social content to build rapport and trust in these non-collaborative settings in order to advance their goals. To handle social content, we introduce a hierarchical intent annotation scheme, which can be generalized to different non-collaborative dialog tasks. Building upon TransferTransfo (Wolf et al. 2019), we propose an end-to-end neural network model to generate diverse coherent responses. Our model utilizes intent and semantic slots as the intermediate sentence representation to guide the generation process. In addition, we design a filter to select appropriate responses based on whether these intermediate representations fit the designed task and conversation constraints. Our non-collaborative dialog model guides users to complete the task while simultaneously keeps them engaged. We test our approach on our newly proposed ANTISCAM dataset and an existing PERSUASIONFORGOOD dataset. Both automatic and human evaluations suggest that our model outperforms multiple baselines in these two non-collaborative tasks.

Introduction: Considerable progress has been made building end-to-end dialog systems for collaborative tasks in which users cooperate with the system to achieve a common goal. Examples of collaborative tasks include making restaurant reservations and retrieving bus time-table information. Since users typically have clear and explicit intentions in collaborative tasks, existing systems commonly classify user utterances into pre-defined intents. In contrast, non-collaborative tasks are those where the users and the system do not strive to achieve the same goal. Examples of such tasks include deceiving attackers, persuading users to donate to a cause BIBREF1, and negotiating a product price BIBREF2, BIBREF3. In these tasks, users often perform complex actions that are beyond a simple set of pre-defined intents. In order to reach a common state, the user and the system need to build rapport and trust which naturally involves off-task content. Previous work did not model off-task content BIBREF2, which may have led to less optimal results. For example, in the persuasion task BIBREF1, users would ask the system “How do you feel about war?" An example of an on-task system response that the system could have made is “Do you want to make a donation?", which sticks to the task but neglects users' question. However, a better response to such an off-task question is “War is destructive and pitiless, but you can donate to help child victims of war." This response is better, as it has been found that users are more likely to end the conversation if the system neglects their questions BIBREF4. Therefore, we need to design a system that handles both on-task and off-task information appropriately and in a way that leads back to the system's goal. To tackle the issue of incoherent system responses to off-task content, previous studies have built hybrid systems to interleave off-task and on-task content. BIBREF4 used a rule-based dialog manager for on-task content and a neural model for off-task content, and trained a reinforcement learning model to select between these two models based on the dialog context. However, such a method is difficult to train and struggles to generalize beyond the movie promotion task they considered. To tackle these problems, we propose a hierarchical intent annotation scheme that separates on-task and off-task information in order to provide detailed supervision. For on-task information, we directly use task-related intents for representation. Off-task information, on the other hand, is too general to categorize into specific intents, so we choose dialog acts that convey syntax information. These acts, such as “open question" are general to all tasks. Previous studies use template-based methods to maintain sentence coherence. However, rigid templates lead to limited diversity, causing the user losing engagement. On the other hand, language generation models can generate diverse responses but are bad at being coherent. We propose Multiple Intents and Semantic Slots Annotation Neural Network (MISSA) to combine the advantages of both template and generation models and takes advantage from the hierarchical annotation at the same time. MISSA follows the TransferTransfo framework BIBREF0 with three modifications: (i) We first concurrently predict user's, system's intents and semantic slots; (ii) We then perform conditional generation to improve generated response's coherence. Specifically, we generate responses conditioned on the above intermediate representation (intents and slots); (iii) Finally, we generate multiple responses with the nucleus sampling strategy BIBREF5 and then apply a response filter, which contains a set of pre-defined constraints to select coherent responses. The constraints in the filter can be defined according to specific task requirements or general conversational rules. To enrich publicly available non-collaborative task datasets, we collect a new dataset AntiScam, where users defend themselves against attackers trying to collect personal information. As non-collaborative tasks are still relatively new to the study of dialog systems, there are insufficiently many meaningful datasets for evaluation and we hope this provides a valuable example. We evaluate MISSA on the newly collected AntiScam dataset and an existing PersuasionForGood dataset. Both automatic and human evaluations suggest that MISSA outperforms multiple competitive baselines. In summary, our contributions include: (i) We design a hierarchical intent annotation scheme and a semantic slot annotation scheme to annotate the non-collaborative dialog dataset, we also propose a carefully-designed AntiScam dataset to facilitate the research of non-collaborative dialog systems. (ii) We propose a model that can be applied to all non-collaborative tasks, outperforming other baselines on two different non-collaborative tasks. (iii) We develop an anti-scam dialog system to occupy attacker's attention and elicit their private information for social good. Furthermore, we also build a persuasion dialog system to persuade people to donate to charities. We release the code and data.

Question: How is intent annotated?
Answer: On-task dialog are annotated as on-task intents , the other dialog are annotated as pre-defined off-task intents.