  Multimodal sentiment analysis (MSA) and emotion recognition in conversation
(ERC) are key research topics for computers to understand human behaviors. From
a psychological perspective, emotions are the expression of affect or feelings
during a short period, while sentiments are formed and held for a longer
period. However, most existing works study sentiment and emotion separately and
do not fully exploit the complementary knowledge behind the two. In this paper,
we propose a multimodal sentiment knowledge-sharing framework (UniMSE) that
unifies MSA and ERC tasks from features, labels, and models. We perform
modality fusion at the syntactic and semantic levels and introduce contrastive
learning between modalities and samples to better capture the difference and
consistency between sentiments and emotions. Experiments on four public
benchmark datasets, MOSI, MOSEI, MELD, and IEMOCAP, demonstrate the
effectiveness of the proposed method and achieve consistent improvements
compared with state-of-the-art methods.
