A wild example of this is from a paper published ~10 years ago: researchers wrote a program that would display an image, then slowly change the color of a signi

A wild example of this is from a paper published ~10 years ago: researchers wrote a program that would display an image, then slowly change the color of a significant object in the image. It was an unmistakable change, like turning a big object red in a grayscale image. When the change was slow enough (IIRC ~20-30 seconds), it would become undetectable to human perception if the person stared at it—even when explicitly told to look for a change. They published a demo video and I remember shocking several people with it. Can’t remember the link. I might have found it through HN.