A New Sentiment-Enhanced Word Embedding Method for Sentiment Analysis

Since some sentiment words have similar syntactic and semantic features in the corpus, existing pre-trained word embeddings always perform poorly in sentiment analysis tasks. This paper proposes a new sentiment-enhanced word embedding (S-EWE) method to improve the effectiveness of sentence-level sentiment classification. This sentiment enhancement method takes full advantage of the mapping relationship between word embeddings and their corresponding sentiment orientations. This method first converts words to word embeddings and assigns sentiment mapping vectors to all word embeddings. Then, word embeddings and their corresponding sentiment mapping vectors are fused to S-EWEs. After reducing the dimensions of S-EWEs through a fully connected layer, the predicted sentiment orientations are obtained. The S-EWE method adopts the cross-entropy function to calculate the loss between predicted and true sentiment orientations, and backpropagates the loss to train the sentiment mapping vectors. Experiments show that the accuracy and macro-F1 values of six sentiment classification models using Word2Vec and GloVe with the S-EWEs are on average 1.07% and 1.58% higher than those without the S-EWEs on the SemEval-2013 dataset, and on average 1.23% and 1.26% higher than those without the S-EWEs on the SST-2 dataset. In all baseline models with S-EWEs, the convergence time of the attention-based bidirectional CNN-RNN deep model (ABCDM) with S-EWEs was significantly decreased by 51.21% of ABCDM on the SemEval-2013 dataset. The convergence time of CNN-LSTM with S-EWEs was vastly reduced by 41.34% of CNN-LSTM on the SST-2 dataset. In addition, the S-EWE method is not valid for contextualized word embedding models. The main reasons are that the S-EWE method only enhances the embedding layer of the models and has no effect on the models themselves