Different visual effects can guide our focus. A fog effect clouds your surroundings and cancels smaller movements. The effect is most potent in the corners of your field of vision. It isn't the most effective one, but the least stressful.
My own research has shown that small flickering squares have the most substantial effect. They induce tunnel vision in the user, but the strong visual effects are very stressful. It can be used to refocus at the start of a session or after an interruption.
The effects will only be applied to the background. Your work area, your hand, and the technology you use stay clear. This prevents a mixed-up depth perception. When your hand appears further away than it is, you can feel uncomfortable.
This creates a clean sheet. A baseline for additional information. It will help us to focus and therefore lift distractions.