title: Recognition of Intensive Valence and Arousal Affective States via Facial Electromyographic Activity in Young and Senior Adults.
abstract: BACKGROUND
  Research suggests that interaction between humans and digital environments characterizes a form of companionship in addition to technical convenience. To this effect, humans have attempted to design computer systems able to demonstrably empathize with the human affective experience. Facial electromyography (EMG) is one such technique enabling machines to access to human affective states. Numerous studies have investigated the effects of valence emotions on facial EMG activity captured over the corrugator supercilii (frowning muscle) and zygomaticus major (smiling muscle). The arousal emotion, specifically, has not received much research attention, however. In the present study, we sought to identify intensive valence and arousal affective states via facial EMG activity.
  
  
  METHODS
  Ten blocks of affective pictures were separated into five categories: neutral valence/low arousal (0VLA), positive valence/high arousal (PVHA), negative valence/high arousal (NVHA), positive valence/low arousal (PVLA), and negative valence/low arousal (NVLA), and the ability of each to elicit corresponding valence and arousal affective states was investigated at length. One hundred and thirteen participants were subjected to these stimuli and provided facial EMG. A set of 16 features based on the amplitude, frequency, predictability, and variability of signals was defined and classified using a support vector machine (SVM).
  
  
  RESULTS
  We observed highly accurate classification rates based on the combined corrugator and zygomaticus EMG, ranging from 75.69% to 100.00% for the baseline and five affective states (0VLA, PVHA, PVLA, NVHA, and NVLA) in all individuals. There were significant differences in classification rate accuracy between senior and young adults, but there was no significant difference between female and male participants.
  
  
  CONCLUSIONS
  Our research provides robust evidences for recognition of intensive valence and arousal affective states in young and senior adults. These findings contribute to the successful future application of facial EMG for identifying user affective states in human machine interaction (HMI) or companion robotic systems (CRS).
authors.affiliation: College of Teacher Education, Lishui University, Lishui, P.R. China.
authors.forename: Jun-Wen
authors.initials: JW
authors.lastname: Tan
authors.affiliation: Biomedical Engineering Laboratory, Faculty of Electrical Engineering, Federal University of Uberlândia, Uberlândia, Brazil.
authors.forename: Adriano O
authors.initials: AO
authors.lastname: Andrade
authors.affiliation: College of Teacher Education, Lishui University, Lishui, P.R. China.
authors.forename: Hang
authors.initials: H
authors.lastname: Li
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Walter
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Hrabal
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Rukavina
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Limbrecht-Ecklundt
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hoffman
authors.affiliation: Emotion Lab, Section Medical Psychology, University of Ulm, Ulm, Germany.
authors.forename: Harald C
authors.initials: HC
authors.lastname: Traue
mesh_terms: D000328:Adult; D000368:Aged; D001143:Arousal / Q000502:physiology*; D004576:Electromyography / Q000379:methods*; D004644:Emotions / Q000502:physiology*; D005145:Face / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult