Robert Plutchik

Plutchik proposed a psychoevolutionary classification approach for general emotional responses.[2][3] He considered there to be eight primary emotions—anger, fear, sadness, disgust, surprise, anticipation, trust, and joy. Plutchik argues for the primacy of these emotions by showing each to be the trigger of behaviour with high survival value, such as the way fear inspires the fight-or-flight response.

Plutchik's psychoevolutionary theory of basic emotions has ten postulates.

1. The concept of emotion is applicable to all evolutionary levels and applies to all animals including humans.
2. Emotions have an evolutionary history and have evolved various forms of expression in different species.
3. Emotions served an adaptive role in helping organisms deal with key survival issues posed by the environment.
4. Despite different forms of expression of emotions in different species, there are certain common elements, or prototype patterns, that can be identified.
5. There is a small number of basic, primary, or prototype emotions.
6. All other emotions are mixed or derivative states; that is, they occur as combinations, mixtures, or compounds of the primary emotions.
7. Primary emotions are hypothetical constructs or idealized states whose properties and characteristics can only be inferred from various kinds of evidence.
8. Primary emotions can be conceptualized in terms of pairs of polar opposites.
9. All emotions vary in their degree of similarity to one another.
10. Each emotion can exist in varying degrees of intensity or levels of arousal.[4][5]

Plutchik's wheel of emotions

Plutchik's wheel of emotions

Plutchik also created a wheel of emotions to illustrate different emotions. Plutchik first proposed his cone-shaped model (3D) or the wheel model (2D) in 1980 to describe how emotions were related.

He suggested 8 primary bipolar emotions: joy versus sadness; anger versus fear; trust versus disgust; and surprise versus anticipation. Additionally, his circumplex model makes connections between the idea of an emotion circle and a color wheel. Like colors, primary emotions can be expressed at different intensities and can mix with one another to form different emotions.

The theory was extended to provide the basis for an explanation for psychological defence mechanisms; Plutchik proposed that eight defense mechanisms were manifestations of the eight core emotions.

The Complex, Probabilistic Sequence of Events Involved in the Development of an Emotion[5]

	Stimulus event	Inferred cognition	Feeling	Behavior	Effect
	Threat	"Danger"	Fear, terror	Running, or flying away	Protection
	Obstacle	"Enemy"	Anger, rage	Biting, hitting	Destruction
	Potential mate	"Possess"	Joy, ecstasy	Courting, mating	Reproduction
	Loss of valued person	"Isolation"	Sadness, grief	Crying for help	Reintegration
	Group member	"Friend"	Acceptance, trust	Grooming, sharing	Affiliation
	Gruesome object	"Poison"	Disgust, Loathing	Vomiting, pushing away	Rejection
	New territory	"What's out there?"	Anticipation	Examining, mapping	Exploration
	Sudden novel object	"What is it?"	Surprise	Stopping, alerting	Orientation

Plutchik contributed the "Emotions" article to the encyclopedia, World Book Millennium 2000.

• The Nature of Emotions, a model that describes the relations among emotion concepts. Plutchik's Theory of Emotions
• The Nature of Emotions (American Scientist Vol. 89, No. 4 (July–August 2001), pp. 344–350)