Going beyond scalable notifcations - from subtle stimulus to forced response

People's perception of their own body's appearance, capabilities and position are constantly updated through sensory cues that are naturally produced by their own actions. Alteration or enhancement of such cues has been carried out with multisensory feedback in multiple Human Computer Interaction (HCI) areas such as health, psychology, neuroscience and games. HCI applications use normally audible or visual alerts, such as LEDs, beeps, bells, among others. However haptic feedback (related to the sense of touch) uses normally other components to augment or replace such common alert methods. Such alerts, also called notifications, usually stick to a binary level of information, while they are either attention drawing or silent. This work proposes a concept that goes beyond scalable notifications, reaching from subtle to obtrusive and also forcing the user to take action. To illustrate the technical feasibility and validity of the concept, three prototypes were developed providing vibrotactile, thermal, and electrical feedback. Each prototype was evaluated in different lab settings suggesting that the concept is applicable in the given situations. It is shown the effect of different notification levels while completing a task and how going beyond an obtrusive level forces the user to execute a desired action such as correct their posture, stop using a tool or press down the gas pedal completely.