Scripted dialogues such as movie and TV subtitles constitute a widespread source of training data for conversational NLP models. However, the linguistic characteristics of those dialogues are notably different from those observed in corpora of spontaneous interactions. This difference is particularly marked for communicative feedback and grounding phenomena such as backchannels, acknowledgments, or clarification requests. Such signals are known to constitute a key part of the conversation flow and are used by the dialogue participants to provide feedback to one another on their perception of the ongoing interaction. This paper presents a quantitative analysis of such communicative feedback phenomena in both subtitles and spontaneous conversations. Based on dialogue data in English, French, German, Hungarian, Italian, Japanese, Norwegian and Chinese, we extract both lexical statistics and classification outputs obtained with a neural dialogue act tagger. Two main findings of this empirical study are that (1) conversational feedback is markedly less frequent in subtitles than in spontaneous dialogues and (2) subtitles contain a higher proportion of negative feedback. Furthermore, we show that dialogue responses generated by large language models also follow the same underlying trends and include comparatively few occurrences of communicative feedback, except when those models are explicitly fine-tuned on spontaneous dialogues.

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