Has Notification Overload Got You Feeling Deflated?

We have so many things fighting for our attention these days. Between our emails, text messages, smartphone and smartwatch notifications, and everything else competing for our eyeballs, it is easy to develop alert fatigue. If everything is treated as important, then at some point, nothing will be more important than anything else. These incessant distractions ultimately reduce user engagement and hinder our ability to effectively respond to real emergencies. The vibrations or audible tones of a notification simply fade into the background and go unnoticed or intentionally ignored.

In an effort to break the monotony and recapture our attention when necessary, researchers at the Université Grenoble Alpes in France have been experimenting with a new type of notification system. Focusing on smartwatches initially, the team is exploring how soft, shape-changing surfaces might be able to better capture our attention than traditional methods that are now commonly in use. Their approach involves the use of a novel surface on the back of a watch that can morph into different shapes to provide us with alerts via tactile sensations. Their hope was that this type of stimulation might be more likely to be noticed and acted upon, even if we are feeling alert fatigue.

To create the prototype device, the team used a stereolithography 3D printer to make a watch-like object with a soft back that can be deformed when inflated with air. The watch case and bracelet were printed in a resin material, while the shape-changing air chamber was printed with a silicone material. When deflated, the backing is as thin as three millimeters. A set of three 12 volt two-way peristaltic air pumps (located external to the watch) were used for actuation of the notification system.

In a series of experiments, participants tested two different designs of shape-changing wrist interfaces to determine the absolute threshold at which they notice the haptic feedback. The independent variable was the design of the air channels that control the curvature of the watch’s surface. Design R had dense and evenly spaced air channels, leading to a flatter curvature at 12 psi. Design P had air channels more spaced at the edges and closer together at the center, producing a pointier curvature at the same pressure. Curvatures were tested in the range of 1 to 13 psi, with significant differences between the two designs emerging at 10 to 13 psi.

Participants wore the bracelet, which was securely fitted to their wrists using a sizing model based on wrist circumference, and half of the participants started with Design R, while the other half began with Design P. Dependent variables included whether participants noticed the stimulus, their preferences, and subjective detectability of the curvatures, measured through a questionnaire and semi-structured interviews.

The experiment results revealed that the absolute detection threshold (ADT) for both the flat-to-round (R) and flat-to-pointy (P) surfaces was low, indicating that participants were sensitive to the shape-changing stimuli. The ADT for the R surface was 3.49 psi, while the P surface had a slightly higher ADT at 4.22 psi, but the difference between the two was minimal. Participants rated both designs as neutral in usability but found them somewhat positive in terms of stimulation quality. Qualitative feedback highlighted that participants found the sensation pleasant, describing it as "smooth" and "soothing."

The results indicate that this new approach may have some advantages over existing alert mechanisms, but before it can be deployed, the inflation system needs to be made much more compact and practical. And then the question arises — if this type of alert becomes common, will it just fade into the background like the rest?