Toward Contextual Valence Shifters in Vietnamese Reviews

Sentiment analysis assumes the task of identifying positive, negative, and neutral thoughts as well as emotional and subjective attitudes of the holder to the target audience, such as products, persons, or topics. Sentiment analysis is emerging as a research field attracting the scientific community. This includes the construction of emotional lexicons as a basis for other sentiment analysis problems at the document level, sentence level, and aspect level. This work can be done in many ways, with the simplest approach being to manually decide the polarities of sentiment words, and then to have a way of identifying the sentiment for each sentence or for the whole document based on the sentiment values of the words. However, this approach is not appropriate for subjectivity analysis because the sentiment values may be changed in context by the so-called valence shifters [1]. Valence shifters (or “polarity shifters”, “sentiment shifter”) are words (or phrases) that can change the sentiment orientations of texts. They are complex linguistic structures that may include explicit negations, contrasts, intensifiers, and diminishers, etc. [2].