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Personality traits

Personality traits correspond to patterns of behavior and modes of thinking that determine a person's adjustment to the environment. They change little and slowly over time, and can be recognized through an individual's behavior, because those traits are what makes this character different from the others. Examples of personality traits are self-confidence, friendliness, and greed.

We base our personality model on two types of psychological theories: the traits theories and the social learning theories. Both theories describe an individual personality profile in terms of a set of traits quantified on a continuous dimension such as the introverted/extroverted scale, and use that profile to predict future behaviors. In trait theories, we assume that people behave consistently, no matter the context. In social learning theories, a person's behavior varies depending on the characteristics of the context and her past experiences with similar situations. For example, a waiter may be shy with women, but self-confident with men.

In our model, the quantification of a trait is numerical, the value being an integer on the interval [-10, 10]. For instance, if we consider the scale of friendliness, -10 would mean that a character is very hostile, 0 that he or she is neither hostile nor friendly, and 10 that he or she is very friendly. We can attribute a default value to a personality trait. Such a value is fixed, as prescribed by trait theories. But, as an alternative, we can define a flexible value correlated to the value of an another trait, mood, or attitude. For instance, we can say that a character has a confidence level of 6 (fixed value) and a friendliness level depending on how much he or she likes the characters he or she is interacting with (correlated value). Finally, we can specify situations when the character has a value different from the default of correlated value, with respect to social learning theories. Those situations apply on values of personality traits, moods, or attitudes. For instance, although a character has a level of friendliness of 5 by default, we could say that this level lowers to -7 if he or she gets very angry.

Moods

Moods are emotions such as happiness and anger, or sensations from physical needs as fatigue, hunger, and thirst. Emotions are triggered by events; sensations are event-independent. We divide the moods into two categories: the self-oriented moods, and the agent-oriented moods.

1) The self-directed moods, such as happiness, pride, and thirst, are not directed toward other characters.

2) The agent oriented moods, such as anger and reproach, are directed toward other individuals.

The distinction between the two kinds of moods is significant, because an individual may have very different feelings for someone from the ones he or she has in general. For instance, one character may be rather happy, but remain angry at another character because of what that character did to him.

Attitudes

Attitudes, such as status, degree of sympathy, and trust, correspond to the essence of an interpersonal relationship. They are different from agent-oriented moods, which are very variable. Attitudes vary slowly over time or remain quite stable, depending on the nature of the relationship.

Rousseau, D., & Hayes-Roth, B. (1997). Interacting with personality-rich characters. Report No. KSL 97, 6.