We study when, where, and why 978 Holocaust survivors smile in video testimonies. We create an automatic smile detection model from facial features with an F1 of 85% and annotate detected smiles under two established taxonomies of smiling. We produce narrative features on 1,083,417 transcript sentences as well as emotional valence from three different modalities: audio, eye gaze, and text transcript. Smiling rates are significantly correlated with specific semantic topics, narrative structures, and temporal syntaxes across the entire corpus. Smiles often occur during periods of intense negative affect; these negative-affect smiles improve the valence trajectory of surrounding sentences significantly across all three modalities. Smiling reduces eye dynamics and blink rates, and the strength of both of these effects is also modulated by narrative valence. Taken together, we conclude that smiling plays a critical role in regulating emotion and social interaction during traumatic recollection.

翻译：我们研究了978名大屠杀幸存者在视频证词中微笑的时间、地点和原因。我们基于面部特征构建了一个自动微笑检测模型（F1分数达85%），并根据两种既定的微笑分类体系对检测到的微笑进行标注。我们针对1,083,417个转录句子提取了叙事特征，并从音频、视线轨迹和文本转录三种模态获取情感效价。在整个语料库中，微笑频率与特定语义主题、叙事结构及时间句法显著相关。微笑常发生于强烈负面情绪期间；这些伴随负面情绪的微笑显著改善了三种模态下周围句子的效价轨迹。微笑降低了眼球动态和眨眼频率，这两种效应的强度均受叙事效价的调节。综合来看，我们得出结论：微笑在创伤回忆中具有调节情绪和社会互动的关键作用。