# Emotional Health Detection in HAR: New Approach Using Ensemble SNN
## 3 Emotion Recognition Analysis
### Detection Technique  
The FER is also used in human intention prediction (HIP), which represents an emerging area of research in which the system, through the collected data, predicts human behavior to improve assisted living. Face recognition in the context of the HAR in healthcare can be applied for:  
* Detecting neurodegenerative disorders;
* Detecting states of depression or, in general, identifying subjects who need assistance;
* Observing the condition of patients during medical treatment;
* Detecting psychotic disorders;
* Monitoring anxiety states;
* Detecting pain or stress. Human behavior can be characterized by analyzing facial expressions through the vision system. The face is the most expressive part of our body; it makes visible every emotional trace, thus making a face the primary source from which to obtain information on emotions. [PERSON] et al. analyzed how emotions can be detected [23]. They can be recognized through unimodal social behaviors, such as speech, facial expressions, texts, or gestures; bimodal behaviors, such as speech associated with facial expressions; or multimodal behaviors, such as audio, video, or physiological signals. As part of our study, we focused on recognizing emotions through facial expression without considering other methodologies that use voice, body movements, or physiological signals. [PERSON] was one of the first researchers to study emotions and their relationship with facial expressions; his research demonstrated the universality and discretion of emotions following Darwinian theory [24]. Over the years, he developed a set for the recognition of emotions based on a series of stimuli called POFA (Pictures of Facial Affect) consisting of 110 black and white images. According to [PERSON] et al. [25], in nature, there are two different categories of emotions, primary or universal emotions, and secondary or complex emotions. The former can also be present in other animals, as [PERSON] argued in _The Expression of Emotion in Man and Animals_; the latter, however, is present only in human beings. Primary emotions are universal and innate emotions. On the other hand, secondary emotions are affected by environmental and socio-cultural influences. The primary emotions are also essential: anger, fear, sadness, happiness, disgust, and surprise. Complex emotions include joy, envy, shame, anxiety, boredom, resignation, jealousy, hope, forgiveness, offense, nostalgia, remorse, disappointment, and relief. In 1992, [PERSON] expanded his list of basic emotions, adding contempt, embarrassment, guilt, and shame to those already known. For each of the primary emotions, there are characteristic elements of the face that allow one to identify the type of emotions:  
Anger, generated by frustration, manifests itself through aggressiveness and can be identified through the following features: a flushed face, hard look, dilated nostrils, clenched jaws, lowered eyebrows, and tight lips. Some of these characteristics are also present in expressions of fear. However, the eyebrows, the forehead movement, and the type of mouth allow us to differentiate the two expressions. In fear, the eyebrows are raised, the eyelids are stretched, and the mouth is open. Happiness, the manifestation of a mood of satisfaction, is one of the easiest emotions to recognize because a smile appears on the person's face. The lips can be joined in the smile or open, including the teeth and cheeks raised. The more pronounced the smile, the more the cheeks rise. Disgust is a feeling of repulsion, and its characteristics are: clenched nostrils, raised upper lip, and curled nose. The greater the sense of disgust, the more pronounced the upper lip and the wrinkling of the nose will be. Sadness is identified through the forehead and eyebrows: the first displays a frown, and for the second, the inner corners are raised. Sometimes sadness can be confused with the emotion of fear.