Here’s a simple exercise to understand how much our perceptions are conditioned. Our perceptions are products of our past experiences of sensory inputs. We have been in rooms millions of times and we have noticed the corners in each of these rooms. When I mentioned a corner in a room, you have an idea, a picture of one. This image is of course your brain just drawing from neurons that have been stimulated from the perceptions you have had of rooms and their corners.
I went back to the city’s art gallery and stayed in the entrance, inside. Below is one corner and I was about 15 feet away from it. I picked this corner because both walls are white and the lights gave it more of a shadow, but the corner (unlike the picture below), is clearly visible.
Just focusing on one spot in the corner where the colors are closely matched, I repeated over and over that the colour is the same that one wall blended into the other. Slowly and after about 4 - 5 minutes, the spot that I focused on, blended into one colour and the corner was gone at that spot. I then extended this image straight up and straight down until the entire walls blended into one.
I looked away for about 60 seconds, and then my eyes went back to the same spot, and I repeated again that the walls blended into one color. This became quicker into getting that image, within 30 seconds. After awhile of repeating this, I got to the point that when I looked at that section and just say the walls blended, I could not see the corner.
When I took some steps in another direction to get a view from a different angle, again repeating that the walls blended into one, I could not see the corner even though I knew that there should be a corner there. My perception told me otherwise.
When I said to myself there’s a corner there, the image became the first image of the corner as in the above picture. When I said the walls blended, the new image came into my view. I switched this back and forth until the blended image became just as fast to become visible as the original image does from having all those millions of neurons of past experiences of seeing rooms and their corners.