Emotions

The emotional personality used a layered model of affect inspired by the ALMA model

(Gebhard, 2005) and the previous emotional model of EVA (Heudin, 2004). There are three

layers corresponding to different kinds of affects which differ in their temporal

characteristics:

 Personality is related to long-term affect which defines the basic mental traits of

the character. We used the Big Five model of personality (McCrae & John, 1992)

that defines the affective behavior by the five traits: openness, conscientiousness,

extraversion, agreeableness and neuroticism.

 Moods are related to medium-term affect which depends mainly on positive and

negative experiences. We used the PAD model (Mehrabian, 1996) which describes

mood with the three traits pleasure (P), arousal (A), and dominance (D). These

three traits are nearly independent and form a three dimensional mood space (see

fig. 2).

 Emotions are related to short-term affect, which is usually bound to an immediate

event or action. After their elicitation these emotions usually decay and disappear

after few seconds.

A Bio-inspired Nano-Agent Architecture for Intelligent Agents 7

There are many relations between these three layers and a modification of one layer has

generally an impact on another layer. Thus, the emotional personality includes an “emotion

engine” which periodically updates the parameters of each layer. As an example, the default

PAD values are computed from the big five traits using the following equations (Mehrabian,

1996):

P = 0.2•Extraversion + 0.59•Agreeableness + 0.19•Neuroticism

A = 0.15•Openness + 0.30•Agreeableness - 0.57•Neuroticism

D = 0.25•Openness + 0.17•Conscientiousness + 0.60•Extraversion - 0.32•Agreeableness

Fig. 2. Mapping of the main moods in the PAD space.