How is it possible to see something without noticing it?

How is it possible to see something without noticing it?

In Telugu it is called kanikaTTu vidya  కనికట్టు విద్య
Knowing what to look for makes it far more likely that you will find it.

 Dr. Marvin Chun, a professor in the Visual Cognitive Neuroscience Lab at Yale, has devoted his career to trying to answer that question. When I visited him on a warm fall afternoon, he invited me to view a video already quite famous in his field of vision and attention. On a monitor I saw six adults standing in the midst of some strange game, their actions frozen by technology. There appeared to be two teams—one dressed in white, one in black.
Each team had a basketball. Strangely, they weren’t on a court but in the corridor of an unidentified office building. Closed elevator doors were clearly visible in the background. My task, once the video started, was to watch the white team and keep track of how many times the ball was passed between players—keeping separate counts of when it was passed overhead and when it was bounced from person to person. The image started to move and I kept my eyes glued to the white team’s basketball as it was passed silently among the moving mass of black and white bodies. I got up to six overhead passes and one bounce pass and I video was complete. Eleven overhead passes and two bounce passes? I ventured. I told Chun that I got a little confused in the middle. Despite that, I’d done a good job, he told me. I missed only one overhead pass. Then he asked, “Did you see anything unusual in the video?” Other than the unusual setting for the game, no, I saw nothing at all out of the ordinary. “Did you see a gorilla in the video?” A gorilla? No, I had definitely not seen a gorilla.

https://www.youtube.com/watch?v=vJG698U2Mvo

 The duck

https://www.youtube.com/watch?v=_bnnmWYI0lM

We have tremendous faith in our ability to see what is in front of our eyes. And yet the world provides us with millions of examples that this is not the case. How often have you been unsuccessful in looking for an object and recruited the help of someone who finds it immediately right in front of you?