Persona effect revisited using bio-signals to measure and reflect the impact of character-based interfaces

The so-called 'persona effect' describes the phenomenon that a life-like interface agent can have a positive effect on the user's perception of a computer-based interaction task. Whereas previous empirical studies rely on questionnaires to evaluate the persona effect, we utilize bio-signals of users in order to precisely associate the occurrence of interface events with users' autonomic nervous system (ANS) activity. In this paper, we first report on the results of an experiment with an agent-guided mathematical game suggesting that an interface character with affective behavior may significantly decrease user stress. Then, we describe a character-based job interview scenario where a user's affective state derived from physiological data is projected back (or 'mirrored') to the user in real-time. Rather than measuring the effect of an interface agent, the focus here is on employing a character as a medium to reflect the user's emotional state, a concept with some potential for emotional intelligence training and the medical domain, especially e-Healthcare.