Red is obviously terrible. Purple is even worse. NPR's Neda Ulaby tells us how purple came to be a scarier color than red. NEDA ULABY, BYLINE: Red is the traditional color of danger, of stop signs ...

If a sign tells you to follow the purple skull ... calls the color-completion effect. The phenomenon causes an image to skew toward the color of the objects that surround it.

Red indicates "unhealthy" air quality, and purple? "Very unhealthy." When did purple become the color more associated with danger? "Red is the color of alert, of stop signs," agrees information ...

Colors are one of the first things people learn about in school. Well, you might have to start re-learning. At least, when it comes to one color people think is on the spectrum. Popular Mechanics ...