Biofeedback interfaces enable dynamic representations of bodily data using sensors and actuators to actively control complex physiological activities. These provide individuals with access to their psychophysiological processes, help regulate bodily responses, and have been shown to have positive effects on affective health and wellbeing.
Traditionally biofeedback has been provided using audiovisual modality whose understanding usually required technical input from physicians. There are still a limited number of biofeedback interfaces that have been deployed from the lab settings to everyday lives. Specifically, there is a limited focus on low-cost, non-screen based, emerging alternative technologies that could support biosensory information in different ways so that users themselves can understand it. To address these challenges, this thesis engages in the design and evaluation of low-cost, wearable smart materials and actuators to support awareness and regulation of affect.
The thesis presents six studies describing them. The first exploration of smart materials and actuators helped in unpacking their material qualities. These include responsiveness, duration, rhythm, aliveness, and range, which led to the design of six wearable visual and haptic interfaces representing physiological arousal. By evaluating the six interfaces in daily life settings, the thesis' findings have shown how the material-driven qualities of the interfaces shape people’s awareness of emotions in different ways starting with reflexivity, emotion identification, and finally, its attribution. This thesis then presents the design of the ThermoPixels toolkit containing digital and physical materials. The toolkit is evaluated by involving users in the design of affective displays for arousal. Findings reveal two distinct motivations for designing physiological arousal interfaces, i.e., awareness and regulation. Analysis of both types of representations helped study their qualities and the role of colors and shapes for personalizing interfaces for awareness and regulation of arousal, i.e., awareness of increased arousal can be supported by angular shapes, warm colors, and rich patterns and regulation of high arousal can be supported by round shapes, cool colors, and light patterns.
Moving forward, the thesis engages in the exploration of heart rate variability to regulate affect. It introduces a mixed-methods approach to compare and evaluate wearable heart rate variability sensors in terms of data quality and user acceptance. Following heart rate variability exploration, the thesis involves users in the design of vibrotactile and temperature patterns for affect regulation and demonstrates the value of personalized haptic patterns in regulating affect as measured by self-reported forms and heart rate variability. Interviews with the haptic group help study haptic patterns' experiential qualities and participants' experiences. Between subjects analysis indicates that subjective and objective measures of anxiety and stress decreased under haptic patterns than without and that low frequency vibration was the most effective pattern for stress regulation. The contribution of this work includes unpacking experiential qualities of high - low frequency vibration and warm - cool thermal patterns for affect regulation by engaging users in their design and guidelines for designing these patterns. Finally, two visual and haptic wearable smartwatch apps i.e., Breathe and Heart are designed for affect regulation. These utilize slow bodily rhythms of breathing and heartbeat and are evaluated in daily life under everyday life situations of high arousal negative affect. Findings show the value of technology-delivered interventions in supporting affect regulation that can augment prior strategies being implemented by individuals in their daily lives. The thesis is concluded with a discussion of research contributions and future directions.
