WIKIMEDIA, PETR NOVAK
The helter-skelter arrangement of letters and numbers that form the ubiquitous Internet security tests known as captchas rely on the visual system’s remarkable ability to easily recognize complex objects regardless of their orientation—a task not even the most sophisticated computer program can match. Two recent studies by neuroscientists at the Salk Institute provide insight into how one part of the visual cortex known as area V4 can distinguish between objects even as they are moved around in space. Their results were published online in Neuron (June 19) and Proceedings of the National Academy of Sciences (June 24).
Area V4 is responsible for intermediate steps of image processing. V4 receives input from early visual brain areas about edges, which V4 assembles to recognize simple geometric shapes. ...
