Brain key to near-perfect visual search

May 9th, 2011 - 7:26 pm ICT by IANS  

Washington, May 9 (IANS) Mammals survive in the wild because they can see and evade predators lurking in the shadowy bushes. This ability to recognise target objects surrounded by distracters is also one of the remarkable functions of the human nervous system.

In the human world, we get out of the house every morning because we find our car keys on that cluttered shelf next to the door.

Visual search is an important task for the brain. Surprisingly, even in a complex task like detecting an object in a scene with distracters, we find that people’s performance is near optimal.

“That means that the brain manages to do the best possible job given the available information,” said Wei Ji Ma, assistant professor of neuroscience at Baylor College of Medicine in the US, who led the study, reports the journal Nature Neuroscience.

“If you are a detective, you weigh different pieces of information based on the reliability of the source. Similarly, the brain has to weigh different pieces of visual information,” said Wei Ji Ma, according to a Baylor statement.

Wei Ji Ma and his colleagues used computer screens to show subjects sets of lines that might or might not contain a line oriented in a particular way.

To manipulate reliability, they randomly varied the contrast of each line, making the target easier or more difficult to detect. Each screen was shown for only a fraction of a second, making the search task very difficult.

“We found that even in this complex task, people came close to being optimal in detecting the target,” he said. “That means that humans can, in a split second, integrate information across space while taking into account the reliability of that information. That is important in our daily lives.”

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