Protocol Competence of Small Language Models in Interactive Language Game Environments

Suchir Salhan, Paula Buttery


Abstract
Learning from interaction requires more than producing appropriate responses: learners must maintain a shared interaction with a partner, following its rules while adapting to feedback and contingencies. We argue that this depends on a prerequisite we call **protocol competence**: the ability to produce valid actions, maintain interaction structure, and respond appropriately across turns. In this paper, we investigate protocol competence in Small Language Models (SLMs) from the Qwen family across five interactive dialogue games from clembench, finding 51.3% of episodes from Qwen3.5-0.8B terminate in protocol violations. However, teacher demonstrations from a larger language model can scaffold participation, raising Wordle play from 0/30 to 29/30. Once models can reliably participate, we find self-improving reinforcement learning becomes effective: a single round of self-generated reinforcement learning (self-ReST) yields large gains from a small number of successful trajectories. Comparing adaptive learning strategies, we find that credit-weighted training provides the most reliable improvements, reducing variance relative to uniform supervision. Together, these results suggest that interactive learning follows a staged trajectory: SLMs must first acquire the competence to participate before they can exploit the contingencies generated by interaction.
Anthology ID:
2026.lmplayschool-1.6
Volume:
The Proceedings of Improving Language Models through Learning from Dialogue Game Interaction
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Alessandro Suglia, Mario Giulianelli, David Schlangen, Raffaella Bernardi, Raquel Fernández, Sherzod Hakimov, Sabrina McCallum, Davide Mazzaccara, Dieu-Thu Le, Oliver Lemon, Alexander Koller
Venues:
LM Playschool | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
57–79
Language:
URL:
https://aclanthology.org/2026.lmplayschool-1.6/
DOI:
Bibkey:
Cite (ACL):
Suchir Salhan and Paula Buttery. 2026. Protocol Competence of Small Language Models in Interactive Language Game Environments. In The Proceedings of Improving Language Models through Learning from Dialogue Game Interaction, pages 57–79, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Protocol Competence of Small Language Models in Interactive Language Game Environments (Salhan & Buttery, LM Playschool 2026)
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PDF:
https://aclanthology.org/2026.lmplayschool-1.6.pdf