50 milliseconds is not a long time. It's about one frame of video, or half as long as the blink of a human eye. And that tiny little slice of time is all it takes for a visitor to a website to decide how appealing that site is.
Dr. Gitte Lindgaard and her team undertook a fascinating study at Carleton University in Ottawa, Canada. Their goal: to determine just how long it takes to make a reliable judgment of the visual appeal of a website. They found that we can accurately judge visual appeal in just 50 milliseconds, or one twentieth of a second! The study was published in Behaviour and Information Technology, March - April 2006.