Tree-Based Interview Topic Guidance for Collecting Target Information under Adaptive Topic continuation/switching
Summary
The paper tackles a tension in interview-style dialogue systems for service recommendation. Adapting topics to the user's mood encourages self-disclosure, but conversations then drift toward whatever the user prefers to discuss, and the system misses information it needs. The authors propose a Question Tree, in which questions are nodes connected by parent–child "follow-up" links. After each user answer, an LLM produces two kinds of candidate questions. Deepening questions probe the current topic further, and approach questions steer toward the target information. The candidates are filtered for naturalness and added to the tree. An external module decides whether to continue or switch topics, and the next question is then picked from the current node's children or siblings. Ranking combines sentence-embedding similarity to the dialogue context and to the target. In Japanese-language simulations with an LLM dummy user and randomly controlled continuation/switching, the method raised target-information collection and made it more consistent across sessions. A small human evaluation found no significant loss of naturalness. This makes tree-based guidance a plug-in complement to existing topic-adaptation modules.
Key points
- Mean target-information collection rate after 10 turns rose from 10.8% (baseline) to 26.6% with the combined method, and variability between sessions decreased.
- Candidate ranking uses a weighted blend, S_blended = r_c·S_c + r_t·S_t. Here S_c is similarity to the current context and S_t is similarity to the target. With several targets, the highest-scoring candidate across all of them is selected.
- Deepening questions are diversified using 5W1H and qualitative-interview probe types. At least one approach question is generated for each target item.
- The experiments used 24 target-information items, translated from Japanese, such as hobbies, days off, flaws and painful experiences. These items are graded by self-disclosure level from 1 to 4.
- Mean processing time per turn was about 4.8 s (range roughly 3.5–6.3 s), and question-candidate generation was the largest component at about 2.4 s.
Cite
@inproceedings{nagasawa2026tree,
title = {{Tree-Based Interview Topic Guidance for Collecting Target Information under Adaptive Topic continuation/switching}},
author = {Nagasawa, Fuminori and Hashimoto, Ekai and Shiramatsu, Shun},
booktitle = {Proceedings of the 27th Annual Meeting of the Special Interest Group on Discourse and Dialogue},
year = {2026},
doi = {10.18653/v1/2026.sigdial-1.35},
url = {https://doi.org/10.18653/v1/2026.sigdial-1.35}
}References
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