title: Implicit data collection
text: # Implicit data collection
  
  Implicit data collection is used in human–computer interaction to gather data about the user in an implicit, non-invasive way.
  
  ## Overview
  
  The collection of user-related data in human–computer interaction is used to adapt the computer interface to the end user. The data collected are used to build a user model. The user model is then used to help the application to filter the information for the end user. Such systems are useful in recommender applications, military applications (implicit stress detection) and others.
  
  ## Channels for collecting data
  
  The system can record the user's explicit interaction and thus build an MPEG7 usage history log. Furthermore, the system can use other channels to gather information about the user's emotional state. The following implicit channels have been used so far to get the affective state of the end user:
  
  * facial activity
  * posture activity
  * hand tension and activity
  * gestural activity
  * vocal expression
  * language and choice of words
  * electrodermal activity
  * eye tracking
  
  ## Emotional spaces
  
  The detected emotional value is usually described any of the two most popular notations:
  
  * a 3D emotional vector: valence, arousal, dominance
  * degree of affiliation to the 6 basic emotions (sadness, happiness, anger, fear, disgust, surprise)
  