Blind People Can 'See', Study Shows  

THE 'psychic' ability of blind people to "sense" unseen objects has been demonstrated for the very first time in sighted volunteers whose vision was blanked out by scientists.

The findings suggest 'blindsight', which has been observed in blind people whose eyes function normally but who have suffered damage to the brain's visual centre, is a real and not imagined phenomenon.

In laboratory tests, the blind have been able to distinguish basic shapes of objects they cannot see, as well as their orientation and direction of motion. On other occasions a blind person has reported experiencing a "feeling" that an object is present, while not being able to see it.

A number of theories have been proposed to explain blindsight, including psychic ones. Generally, it is suggested that other parts of the brain besides the primary visual cortex respond to nerve messages from the eyes at an unconscious level.

Scientists from the University of Houston in Texas, temporarily blinded a group of twelve volunteers by using an electromagnetic field in order to shut down the primary visual cortex. Images were then flashed in front of the volunters on a screen.

In one experiment, the volunteers were shown either a horizontal or vertical bar. In another test, a red or green dot appeared.

Most of the time, the volunteers were unaware of the images with which they were presented. But they guessed either the orientation of the bar or the colour of the dot correctly more often than would have been expected by the law of averages.

The researchers wrote in the journal Proceedings of the National Academy of Sciences: "Despite unawareness of these 'targets', performance on forced-choice discrimination tasks for orientation and colour were both significantly above chance."

They said the findings suggested that a visual pathway bypassing the primary visual cortex must be responsible for blindsight.

A team of psychologists at Rice University in Houston, Texas, may have found a way to directly study blindsight in the lab.

They are using electromagnetic stimulation on the brains of people who can see to render them partially and temporarily blind.

"The way it works is an electric current inducts into the brain via a magnetic pulse, and that causes a disruption of underlying neurons in the brain," said Tony Ro, a member of the Rice team.

"What this technique allows us to do essentially is in a safe and noninvasive way shut down a portion of the brain temporarily," he added.

Ro and colleagues report their technique and findings in the current issue of the journal Proceedings of the National Academy of Sciences.

Mole said the Rice team reports "compelling proof" for blindsight.


Source:

http://www.scotsman.com/?id=2176562005