In 1980 Robert Plutchik constructed a wheel-like diagram of emotions, an infograph that uses the color wheel to illustrate variations in human affect and the relationship among emotions. Current applications of the wheel of emotion include robotics and sentiment analysis.
Psychologist Robert Plutchik created the 2D wheel and a conical 3D version in 1980 as a tool for understanding his psychoevolutionary theory of emotion. Plutchik identified eight primary emotions, which he coordinated in pairs of opposites (see table).
Intensity of emotion and indicator color increases toward the center of the wheel and decreases outward. At the center, terror, for example, becomes fear and then apprehension; ecstasy becomes joy and then serenity. Secondary emotions are displayed as combinations of the primary ones.
ConveyAPI, a web service that interfaces with a text analysis engine, applies the wheel of emotions to sentiment analysis for social media monitoring. ConveyAPI uses the concepts of Plutchik's wheel of emotions in text analysis to identify the polarity (positive or negative) and attribute specific emotions and their intensity.