reel and real

When you look at a moving wheels/fan blades in a movie or under the baleful glare of a tubelight, especially when speeding up, there is a point where they appear to slow down, stop, and go backwards. That's old news. What you didn't know is that something in our very brains can cause this, even in direct sunlight... or at least according to the author of this article: http://www.pnas.org/content/93/8/3693.abstract