On July 20 news, Scientific American reported on research that showed that intension influences perception.
In simplified terms, when we are looking for some characteristics in a visual search, the visual processing nurons can sensitize the entire visual field to recognize what we are "looking for" more quickly.
"In feature-based attention, neurons form the search patterns we use to find familiar objects in unexplored places"
From the fMRI data, the researchers could see that, as they had expected, different subpopulations of neurons in the brain were also activated when the subjects were asked to concentrate on stimuli moving up and left versus up and right. The surprise came when they noticed that a pattern of activity among the neurons that process the lower half of the visual field echoed the behavior of the cells for the field's upper half.
"While [the subjects are] attending to a particular direction of motion, the part of the brain that processes that direction of motion becomes more sensitized to detect that … motion," Serences says. "The really new thing is the fact that this sensitization spreads across the entire visual field." This indicates that while you are consciously tuning for a particular shape or color—say, your lost keys—in one part of your visual field, you may be subconsciously alerting the entire visual system to that trait, enabling a more efficient search.