Beyond Sentiment: The Manifold of Human Emotions

Sentiment analysis predicts the presence of positive or negative emotions in a text document. In this paper we consider higher dimensional extensions of the sentiment concept, which represent a richer set of human emotions. Our approach goes beyond previous work in that our model contains a continuous manifold rather than a finite set of human emotions. We investigate the resulting model, compare it to psychological observations, and explore its predictive capabilities. Besides obtaining significant improvements over a baseline without manifold, we are also able to visualize different notions of positive sentiment in different domains.Comment: 15 pages, 7 figure

The Linguistics of Sentiment Analysis

Computational linguistics is a field that was founded by linguists, but more recently is the domain of more computer scientists than linguists. Use of data driven and machine learning methods for computational linguistics applications is now more common than handwritten linguistic rules. In order for a linguist to enter the field, it is essential that he or she be familiar with methods and techniques from computer science. The purpose of this paper is twofold. The first is to serve as a linguist\u27s introduction to concepts from outside of linguistics that are used in computational linguistics. The second purpose is to illustrate the use of linguistic features for a specific task known as sentiment analysis. This task involves determining the sentiment of a piece of text. By way of examining linguistics within sentiment analysis, this paper will begin to gesture at the potential role for linguists in the modern field of computational linguistics as a whole. The goal is to encourage and enable linguists to reengage with computational linguistics by providing a suitable introductory work

Comparing the utility of different classification schemes for emotive language analysis

In this paper we investigated the utility of different classification schemes for emotive language analysis with the aim of providing experimental justification for the choice of scheme for classifying emotions in free text. We compared six schemes: (1) Ekman's six basic emotions, (2) Plutchik's wheel of emotion, (3) Watson and Tellegen's Circumplex theory of affect, (4) the Emotion Annotation Representation Language (EARL), (5) WordNet–Affect, and (6) free text. To measure their utility, we investigated their ease of use by human annotators as well as the performance of supervised machine learning. We assembled a corpus of 500 emotionally charged text documents. The corpus was annotated manually using an online crowdsourcing platform with five independent annotators per document. Assuming that classification schemes with a better balance between completeness and complexity are easier to interpret and use, we expect such schemes to be associated with higher inter–annotator agreement. We used Krippendorff's alpha coefficient to measure inter–annotator agreement according to which the six classification schemes were ranked as follows: (1) six basic emotions (a = 0.483), (2) wheel of emotion (a = 0.410), (3) Circumplex (a = 0.312), EARL (a = 0.286), (5) free text (a = 0.205), and (6) WordNet–Affect (a = 0.202). However, correspondence analysis of annotations across the schemes highlighted that basic emotions are oversimplified representations of complex phenomena and as such likely to lead to invalid interpretations, which are not necessarily reflected by high inter-annotator agreement. To complement the result of the quantitative analysis, we used semi–structured interviews to gain a qualitative insight into how annotators interacted with and interpreted the chosen schemes. The size of the classification scheme was highlighted as a significant factor affecting annotation. In particular, the scheme of six basic emotions was perceived as having insufficient coverage of the emotion space forcing annotators to often resort to inferior alternatives, e.g. using happiness as a surrogate for love. On the opposite end of the spectrum, large schemes such as WordNet–Affect were linked to choice fatigue, which incurred significant cognitive effort in choosing the best annotation. In the second part of the study, we used the annotated corpus to create six training datasets, one for each scheme. The training data were used in cross–validation experiments to evaluate classification performance in relation to different schemes. According to the F-measure, the classification schemes were ranked as follows: (1) six basic emotions (F = 0.410), (2) Circumplex (F = 0.341), (3) wheel of emotion (F = 0.293), (4) EARL (F = 0.254), (5) free text (F = 0.159) and (6) WordNet–Affect (F = 0.158). Not surprisingly, the smallest scheme was ranked the highest in both criteria. Therefore, out of the six schemes studied here, six basic emotions are best suited for emotive language analysis. However, both quantitative and qualitative analysis highlighted its major shortcoming – oversimplification of positive emotions, which are all conflated into happiness. Further investigation is needed into ways of better balancing positive and negative emotions. Keywords: annotation, crowdsourcing, text classification, sentiment analysis, supervised machine learnin