  Emotion Recognition in Conversation (ERC) has been widely studied due to its
importance in developing emotion-aware empathetic machines. The rise of
pre-trained language models (PLMs) has further pushed the limit of ERC
performance. However, most recent works on ERC using PLMs are heavily
data-driven, and requires fine-tuning the entire PLMs. To improve both sample
and computational efficiency, we propose a derivative-free optimization method
called Cross-Task Prompt Tuning (CTPT) for few-shot conversational emotion
recognition. Unlike existing methods that learn independent knowledge from
individual tasks, CTPT leverages sharable cross-task knowledge by exploiting
external knowledge from other source tasks to improve learning performance
under the few-shot setting. Moreover, CTPT only needs to optimize a vector
under the low intrinsic dimensionality without gradient, which is highly
parameter-efficient compared with existing approaches. Experiments on five
different contextual conversation datasets demonstrate that our CTPT method has
superior results on both few-shot scenarios and zero-shot transfers.
