Occasionally we look for something that is right in front of us, yet at first we don't see it. This demonstrates how dominant the 'cognitive' aspect of vision is; how to see something is not merely to look at it — to absorb the light from it — but to recognise it. That is, to map the visual data onto some conceptual model that accords with the object we seek.
I was looking for the toothpaste on the bathroom sink. It took me some moments to see it, although it was in my visual field all the time. It was not my visual system that was deficient, but my conceptual attention.
This example might be used to show that objects do not exist in the world until they are conceptualised. Unconceived objects are invisible.
(A similar incident occurred when looking for the soap. I scanned the room, including the area where the soap was, but had already moved on when I realised where the soap was. It took a fraction of a second to conceptualise what I had seen)
(A further incident: I was looking for a tape measure that I believed to be green. I knew where it was but couldn't see it. It turned out the measure was actually yellow. Although I had looked at it several times I had not seen it because it didn't look like I expected it to look.)
