The most famous of these tests was the Invisible Gorilla.
"These confounding findings from cognitive psychologists Daniel Simons and Christopher Chabris detailed in a 1999 study revealed how people can focus so hard on something that they become blind to the unexpected, even when staring right at it. When one develops 'inattentional blindness,' as this effect is called, it becomes easy to miss details when one is not looking out for them.
'Although people do still try to rationalize why they missed the gorilla, it's hard to explain such a failure of awareness without confronting the possibility that we are aware of far less of our world than we think,' Simons told LiveScience."
http://viscog.beckman.illinois.edu/flashmovie/15.phpSame deal. Count the number of times the White shirts pass the basketball.