There are five (5) classes of emotion theory:
1. Adaptive Responses - emotions which are adaptive responses with their specific mental states;
2. Response Feedback - emotions are mental states produced by bodily response states;
3. Neural Systems - emotions are behaviours and mental states due to specific neural systems;
4. Cognitive Appraisal - emotions are mental states that give rise to appropriate behaviours;
5. Frustration and Conflicts - emotions are thwarted aroused actions states in CNS and body.
Resources: William James (1890)Book of Emotions
