Exploring Eye-Blink Startle Response as a Physiological Measure for Affective Computing

In affective computing, detection of stress and negative emotions with physiological measures typically employs well-known signals such as skin conductance, activity of cheeks and forehead muscles, heart rate or heart rate variability. However, psychophysiology experiments in the literature offer additional measures (such as eye-blink startle response) not yet exploited in affective computing applications. Procedures to elicit eye-blink startle responses are often based on acoustic stimuli, in particular short bursts of intense white noise. Unfortunately, following this approach in affective computing applications would not be natural, because the artificial white noise bursts would be intrusive sounds unrelated to the user experience. They would thus distract the user from the meaningful events in the application and user's (conscious or unconscious) attempts to relate those events to the artificial stimuli would be unsuccessful and frustrating, making the stimuli detrimental to the user experience. Our research aims at exploring if sounds that have a meaningful relation with the events in the application could be used as an alternative to white noise bursts. The study we present in this paper compares physiological responses of users of a 3D virtual environment in two conditions (measurement of eye-blink startle response to white noise or to an alternative sound that is related to the experience), showing that the two types of acoustic stimuli produce a similar intensity of startle response. This result suggests that eye-blink startle response could be used in natural ways to extend the set of physiological measures employed in affective computing.