Internal Consistency of Physiological Responses during Exposure to Emotional Stimuli using Biosensors

In biomedical engineering application, mental/physical health monitoring using biosensors has been lately noticed because bio-signal acquisition by non-invasive sensors is relatively simple as well as bio-signal is less sensitive to social/cultural difference. In particular, although it is known that they are significantly correlated with human emotional state, whether the signals by various emotions are stable remains unknown. In this study, we examined the consistency of physiological responses induced by six basic emotions, happiness, sadness, anger, fear, disgust and surprise using an experiment that was repeated 10 times. Twelve college subjects participated in this experiment. For emotion induction, sixty different emotional stimuli were selected in a pilot experiment. Heart Rate (HR), Skin Conductance Level (SCL), mean of Skin Temperature (meanSKT), and mean of Photoplethysmograph (meanPPG) were measured before the presentation of stimuli as a baseline and during the presentation of the stimuli as emotional state. The results showed that physiological responses during emotional states for the 10 times the experiment was repeated were stable and consistent compared to the baseline. In particular, we could identify that physiological features such as SCL, HR, and PPG are very reliable. Our results suggest that bio-signals by six emotions are consistent over time regardless of various stimuli. This means that physiological responses are reliable and biosensors are useful tool for emotion recognition.