Morning dear friends,

It's a sunny day here in Norfolk, and very mild again...

...my paralysis is still dreadful, with neck, arm and leg movements now extremely limited, but I seek a glimmer of hope in every movement possible. :)

...as I'm dealing with M.E. I found this article quite interesting, as the mind has always fascinated me, with it's oddities and profundities.

Finding a friend in a crowd, searching for a nickel in a pile of coins, and locating a jar of mustard in the refrigerator are examples of visual search tasks. Two University of Iowa, Iowa City, researchers have made an important step forward in understanding how these tasks are performed by the human visual system.

Geoffrey F. Woodman, a graduate student, and Steven J. Luck, associate professor of psychology, found that, when humans look at collections of objects, attention is focused on a single object at a time and moves from one to the next in about a tenth of a second. Research has shown that the more complex a visual image is, the longer it takes for the human brain to process the entire scene. Scientists have long debated the reason for this, with some arguing that the longer processing time indicates serial processing and others believing that it indicates parallel processing.

As an analogy, Luck notes that serial processing is like a construction company with 100 employees who work together to build one house at a time, whereas parallel processing is like a company that erects 10 houses simultaneously with 10 employees working on each house. Similarly, the human brain might devote all of its capacity to one object at a time and shift rapidly from one to the next, or it might process all of the objects in a visual scene nearly simultaneously, with just a fraction of the brain's capacity devoted to each.

Woodman and Luck are the first to show definitively that the human brain processes complex images serially--attending to one thing at a time, but shifting rapidly from object to object. "This may seem counterintuitive because it doesn't feel like we perceive only one object at a time," Luck indicates. Although it may seem that when you look at a scene you are seeing the whole picture, each object in the scene commands your attention in rapid succession.

The researchers demonstrated serial processing by having subjects search for a specific object in a display containing many other objects. They were shown a group of squares and told to search for the one with a gap in the left side. Most of the squares were black, but the picture also included one red and one green square on opposite sides of the image. The subjects were told that the target square probably would be red, but might be green. This was done to bias the subjects to search in a specific order.

Woodman and Luck used EEG recordings, which monitor brain waves in the same way as an EKG monitors heart activity. To track attention with the EEG, they measured a brain wave that indicates where attention is focused. They found that attention, as indicated by this brain wave, shifted rapidly from the red square on one side of the image to the green square on the other, which demonstrates serial processing.

Woodman compares this type of visual activity to searching for a piece of a jigsaw puzzle among a pile of pieces that will make up the completed picture. You can ignore pieces that are the wrong color, just as the subjects in his experiment ignored the black squares. Once you find several pieces that are the right color, though, you must focus your attention on them individually to see if they also have the correct shape.

Luck says this research will contribute to the long-standing quest to understand exactly how human vision works, which some day may lead to computerized visual systems. He cautions, however, that there is still a long way to go before robots or other forms of artificial intelligence that can match human vision can be created. "A huge proportion of the brain is devoted to vision. We have so much brain power devoted to vision that perceiving scenes seems easy, but it is really an incredibly complex process."

from, Society for the Advancement of Education.