What is an emotion? More than 90 definitions have been offered over the past century, and there are almost as many theories of emotion not to mention a complex array of overlapping words in our languages to describe them. Plutchik offers an integrative theory based on evolutionary principles. Emotions are adaptive in fact, they have a complexity born of a long evolutionary history and although we conceive of emotions as feeling states, Robert Plutchik developped The Nature of Emotions showing that the feeling state is part of a process involving both cognition and behavior and containing several feedback loops.
Another model that is conceptually similar to Plutchik’s “color wheel” model is the tree-like taxonomy proposed by Philip Shaver and his colleagues based on research they conducted with college students. The students rated 213 emotion terms for how typical they are and how much emotion they convey. On the basis of the students’ descriptions, the researchers arrived at 5 to 6 clusters that they believe represent basic emotion categories. The figure below presents the treelike, hierarchical nature of the students’ descriptions of how “emotional” they perceive the emotion like words to be, with overlapping terms falling within the basic categories.