Scaling notifications beyond alerts: From subtly drawing attention up to forcing the user to take action

Research has been done in sophisticated notifications, still, devices today mainly stick to a binary level of information, while they are either attention drawing or silent. We propose scalable notifications, which adjust the intensity level reaching from subtle to obtrusive and even going beyond that level while forcing the user to take action. To illustrate the technical feasibility and validity of this concept, we developed three prototypes. The prototypes provided mechano-pressure, thermal, and electrical feedback, which were evaluated in different lab studies. Our first prototype provides subtle poking through to high and frequent pressure on the user's spine, which significantly improves back posture. In a second scenario, the user is able to perceive the overuse of a drill by an increased temperature on the palm of a hand until the heat is intolerable, forcing the user to eventually put down the tool. The last application comprises of a speed control in a driving simulation, while electric muscle stimulation on the users' legs, conveys information on changing the car's speed by a perceived tingling until the system forces the foot to move involuntarily. In conclusion, all studies' findings support the feasibility of our concept of a scalable notification system, including the system forcing an intervention.