Early on in my academic career, I did research in a middle school classroom. Computers were just introduced to a bunch of kids that never experienced them directly before. There were very few computers in schools at the time, and students were bunched up in groups around each one. One kid got to sit and control the keyboard, another student controlled the mouse. (I bet you know the genders of these two kids.) Most kids just focused their attention on the screen. The task was to familiarize with how the desktop computer interface worked.
At the end of the activity, I got to interview the kids. One of the surprises was how many of the kids didn’t associate the movement of the mouse with the action on the screen. To connect the two actions together, a kid would have had to know that mouse movements and a pointer were related. It was not an obvious observation, especially in a tight crowd of a student group around the computer screen. And to this day, this required double focus is difficult for kids on the Autistic spectrum (iPads are much more intuitive for this population). One of the conclusions of my study — Werby, O. (1994). “The Relationship Between Changes in Perceptual Focus and Understanding,” 1994 AERA Conference, ERIC #: ED370971 — was the explicit need to teach kids what was important and what to pay attention to.
Almost 20 years later, my son sent me this video example of the same phenomena:
When I hear comments like: “Didn’t he see the human legs?” My answer is that this man is suffering from Perceptual Blindness. Many television video programs can be made by exploiting this phenomenon, and magicians do it all the time!