New imaging techniques used on macaque monkeys explains why we find it so easy to scan many items quickly when we’re focused on one attribute, and how we can be so blind to attributes and objects we’re not focused on.
The study reveals that a region of the visual cortex called V4, which is involved in visual object recognition, shows extensive compartmentalization. There are areas for specific colors; areas for specific orientations, such as horizontal or vertical. Other groups of neurons are thought to process more complex aspects of color and form, such as integrating different contours that are the same color, to achieve overall shape perception.
 . Functional organization for color and orientation in macaque V4. Nat Neurosci [Internet]. 2010 ;13(12):1542 - 1548. Available from: http://dx.doi.org/10.1038/nn.2676