Brain can process images in just 13 milliseconds

A team of neuroscientists has found that the human brain can process a dozen pictures that the eye sees for as little as 13 milliseconds.

In the new study, researchers asked subjects to look for a particular type of image, such as "picnic" or "smiling couple," as they viewed a series of six or 12 images, each presented for between 13 and 80 milliseconds.

"The fact that you can do that at these high speeds indicates to us that what vision does is find concepts. That's what the brain is doing all day long- trying to understand what we're looking at," senior author of the study Mary Potter, an MIT professor of brain and cognitive sciences, said.

This rapid-fire processing may help direct the eyes, which shift their gaze three times per second, to their next target, Potter said.

The researcher said that the job of the eyes is not only to get the information into the brain, but to allow the brain to think about it rapidly enough to know what you should look at next.

After visual input hits the retina, the information flows into the brain, where information such as shape, color, and orientation is processed. In previous studies, Potter has shown that the human brain can correctly identify images seen for as little as 100 milliseconds.

The team found that although overall performance declined, subjects continued to perform better than chance as the researchers dropped the image exposure time from 80 milliseconds to 53 milliseconds, then 40 milliseconds, then 27, and finally 13- the fastest possible rate with the computer monitor being used.

The study offers evidence that "feedforward processing" - the flow of information in only one direction, from retina through visual processing centers in the brain - is enough for the brain to identify concepts without having to do any further feedback processing.

It also suggests that while the images are seen for only 13 milliseconds before the next image appears, part of the brain continues to process those images for longer than that, Potter said.

The study was published in the journal Attention, Perception, and Psychophysics.