We usually think we can see the world around us in sharp detail.
In reality, that’s only true for a tiny patch our field of vision, scientists say—an area about the size of the thumbnail of our outstretched hand. The rest is blurred. But the brain fools us into thinking otherwise by using memory to fill in the blanks, a new study by two psychologists concludes.
“We believe that we see the world uniformly detailed,” said Arvid Herwig of the Bielefeld University in Bielefeld, Germany, who investigated the issue with Werner X. Schneider, also of the university.
In reality, “we do not see the actual world, but our predictions” of how it would appear if we examined each part individually, Herwig said. The findings are published in the Journal of Experimental Psychology: General.
Only the central area of the retina—the light-sensitive tissue in the eyeball—can process objects in sharp detail, Herwig said. That area is called the fovea, and it gives us a precise view of an area the size of an outstretched thumbnail. All impressions we get outside the fovea become progressively coarse, Herwig said.
Herwig and Schneider hypothesized that people learn through countless eye movements over a lifetime to connect the coarse impressions of objects outside the fovea to the detailed visual impressions after the eye has moved to the object of interest.
For example, the first time we see a football it may appear as a blurry blob out of the corner of our eye. But when we look at it directly, a detailed image appears. The brain then connects the two impressions—blurry and detailed. In future encounters with footballs, they appear to us as perfect even before we take a direct look: we fill in the missing information from our collection of stored images.
The psychologists used eye-tracking experiments to test their idea. They measured eye movements with a camera that records 1,000 images per second. Participants in their study were given objects to look at, but unbeknownst to them, some objects were changed during eye movement. The aim was to cause the participants to learn new connections between impressions from inside and outside the fovea—detailed and coarse impressions. That learning indeed happened, according to the investigators, and in just a few minutes.
Source : http://www.world-science.net