The visual system is hierarchically organized into different areas. The lower visual areas see small parts of the visual field, and they are sensitive to very simple features, such as edges and their orientation. Higher up the hierarchy, the visual areas start encoding more abstract representations of the world, expanding their visual field to respond to stimuli such as objects and faces.

At the same time, the areas that see “the big picture” send back information to the lower visual areas, called “feedback” connections. Feedback connections are considered essential for integrating contextual information, namely by providing information to lower visual areas about the broader scene, rather than just the small, specific part of the image they are looking at.