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A signal-flow model for the design of social biofeedback systems McCaig, Ronald Graeme


This paper explores the design of ’social biofeedback systems’ (SBFS’s) by presenting a theoretical ’signal-flow model’ and a particular system design called 2Hearts. A proposed definition is given of SBFS’s as systems which sense and display biosensor-derived data in real-time, involve multiple people in social-communication, and convey information relative to emotion or affect. Previous SBFS systems and other related works are reviewed to show both the pattern of interest in such systems and the lack of an underlying theoretical framework. The signal-flow model is developed in detail with reference to literature from psychology, auditory display and affective computing; in its current form the model is focused on SBFS’s which employ heart-sensor data as input and audio as output. Key features of the model are a distinction between conscious and unconscious perception/processing of emotional information, and identification of several different representations of affect information within the brain that are useful for SBFS’s to replicate or process. Suggested design tools are described including SBFS design-goal ’paradigms’ and a high-level SBFS design procedure, framed in terms of the signal-flow model. The design and implementation of the 2Hearts system is described and justified according to the signal-flow model. The 2Hearts system incorporates time-compression/looping techniques to display different heart-data-derived variables in a synchronized, layered fashion, leading to the perception of rhythmic, musical audio patterns. The design and results of 2Hearts user testing are described. Significant testing results are obtained which characterize the emotional associations of some of the 2Hearts audio-display mappings, and lead to suggestions for improvement of these mappings. Other significant results suggest that people can voluntarily influence each others’ heart rates using communicative strategies, thus validating one important assumption of SBFS design. Recommendations are given for future development of the 2Hearts system, the signal-flow model, and the user testing strategies.

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