Using the EMFi chair to measure the user’s emotion-related heart rate responses

Abstract

The research reported here is part of a multidisciplinary collaborative project that aimed at developing embedded measurement devices using electromechanical film (EMFi) as a basic measurement technology. The present aim was to test if an unobtrusive heart rate measurement device, the EMFi chair, had the potential to detect heart rate changes associated with emotional stimulation. Six-second long visual, auditory, and audiovisual stimuli with negative, neutral, and positive emotional content were presented to 24 participants. Heart rate responses were measured with the EMFi chair and with earlobe photoplethysmography (PPG). Also, subjective ratings of the stimuli were collected. Firstly, the high correlation between the measurement results of the EMFi chair and PPG, r = 0.99, p < 0.001, indicated that the EMFi chair measured heart rate reliably. Secondly, heart rate showed a decelerating response to visual, auditory, and audiovisual emotional stimulation. The emotional stimulation caused statistically significant changes in heart rate at the 6th second from stimulus onset so that the responses to negative stimulation were significantly lower than the responses to positive stimulation. The results were in line with previous research. The results show that heart rate responses measured with the EMFi chair differed significantly for positive and negative emotional stimulation. These results suggest that the EMFi chair could be used in HCI to measure the user’s emotional responses unobtrusively.