New methods for unobtrusive monitoring of computer users' emotion psychophysiology are very much needed in human-computer interaction research. The present aim was to study heart rate changes during emotionally provocative stimulation. Six-second long auditory, visual, and audiovisual emotionally negative, neutral, and positive stimuli were presented to 24 participants. Heart rate responses were measured with a regular office chair embedded with electromechanical film (the EMFi chair) and with traditional earlobe photoplethysmography (PPG). Ratings of the stimuli were also collected. The results showed that the two heart rate measurements were significantly correlated, r = 0.99. In line with other studies the results showed that, in general, heart rate decelerated in response to emotional stimulation and it decelerated the most in response to negative stimuli as compared with responses to positive and neutral stimuli. Especially, emotional stimulation caused significant changes in heart rate at the 6 th second from the stimulus onset. We suggest that the EMFi chair could be used in human-computer interaction for unobtrusive measurement of the user's emotional reactions.

The present aim was to explore heart rate responses when stimulating participants with technology primarily aimed at the rehabilitation of older adults. Heart rate responses were measured from 31 participants while they listened to emotionally provoking negative, neutral, and positive musical clips. Ratings of emotional experiences were also collected. The results showed that heart rate responses to negative musical stimuli differed significantly from responses to neutral stimuli. The use of emotion-related physiological responses evoked by stimulating devices offers a possibility to enhance, for example, emotionally stimulating or otherwise therapeutic sessions.

The aim of the present paper was to study heart rate changes during a video stimulation depicting two actors (male and female) producing dynamic facial expressions of happiness, sadness, and a neutral expression. We measured ballistocardiographic emotion-related heart rate responses with an unobtrusive measurement device called the EMFi chair. Ratings of subjective responses to the video stimuli were also collected. The results showed that the video stimuli evoked significantly different ratings of emotional valence and arousal. Heart rate decelerated in response to all stimuli and the deceleration was the strongest during negative stimulation. Furthermore, stimuli from the male actor evoked significantly larger arousal ratings and heart rate responses than the stimuli from the female actor. The results also showed differential responding between female and male participants. The present results support the hypothesis that heart rate decelerates in response to films depicting dynamic negative facial expressions. The present results also support the idea that the EMFi chair can be used to perceive emotional responses from people while they are interacting with technology.

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