Introduction to the special section on the structure of emotion

This section is devoted to articles about the structure of affect, the patterned interrelations of moods and emotions. Structural features of affect, such as a bipolar pleasantness-unpleasantness dimension, a circumplex ordering, prototypical discrete emotions, and separable positive and negative emotion clusters, are discussed. It is proposed that positive and negative affect systems create the conditions for the co-occurrence of discrete positive emotions with each other and of discrete negative emotions with each other. The experience of affect tends to be felt along a bipolar pleasantness-unpleasantness dimension because pleasant emotions and unpleasant emotions tend not to be experienced together at intense levels. To move beyond current knowledge, future research in the area must more often use non-self-report measures, more sophisticated statistical and measurement methods, dynamic as well as static data, systematically varied response formats, and experimental manipulations.