Emotional models describe possible affective states, their causal relationships and patterns of expression.
The most famous of these are probably those given by Paul Ekman, from research on universal facial expressions: fear, anger, sadness, happiness and joy.

An example: output of expressions of empathy in GRETA.

Several models for affective fusion are experimented in CALLAS. The  PAD  dimensional model (that defines a three-dimensional space where individuals are represented as points, personality types are represented as regions and personality scales are represented as straight lines passing through the intersection point of the three axes) is experimented for example in the MusicKiosk and in the e-Tree: a weighted sum of the individual PAD vectors (Pleasure, Arousal, Dominance) provide for e-Tree: a scaled size of tree and leaves, relative thickness of branches, colour of leaves and tropism of branches relative to "ground".



Suggested reading: the point of view of an artist on CALLAS Newsletter1 and scientific papers and articles:

• PAD-based Multimodal Affective Fusion: Abstract
• Using Affective Trajectories to Describe States of Flow in Interactive Art: Abstract
• An Emotionally Responsive AR Art Installation: Abstract
• An Affective Model of User Experience for Interactive Art: Abstract
• The use of affective and attentive cues in an empathic computer-based companion: Abstract