Symbolized the staff patients squeezed to make their veins stand out.

Often added in the U.S., it is sometimes interpreted as representing venous blood (as opposed to arterial red) or simply patriotic colors. 2. The Barber Pole Illusion

In psychology and physics, the "Barber Pole Illusion" is a famous visual phenomenon. When a cylinder with diagonal stripes rotates horizontally, the brain perceives the stripes as moving rather than around the cylinder. This happens because the brain prioritizes the motion along the vertical edges of the "aperture" (the pole's frame). A moving-barber-pole illusion | JOV - Journal of Vision