60-Second Mind

A Blind Man Sees

A recent paper in Current Biology provides one of the few human cases of blindsight, the ability for perceptively blind people to respond to visual stimuli, even though they have no awareness of seeing anything. Christie Nicholson reports.














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[Below is the original script. But a few changes may have been made during the recording of this audio podcast.]

Given that we just said goodbye to another year, we are all pretty familiar with the hindsight. But have you heard of blindsight?

The phenomenon is the ability to see without having the visual brain hardware to actually see. It’s been proven that monkeys have blindsight for navigating through a space, but never in a human, until now.

A recent paper in Current Biology describes a patient who lost his ability to see after suffering strokes that wiped out his visual cortex, the brain area that processes visual input. His eyes and optic nerves remained intact, and the researchers confirmed that some information was being gathered via his still-functioning eyes.

So they gave him what many would think was the impossible test for a blind person. He had to navigate a hallway, around chairs and boxes, without his cane.

He passed the test perfectly. What this implies is that visual information can reach areas of the brain, by routes other than the visual cortex. Meaning, we don’t have to be conscious of the experience of seeing to capture, and respond to, visual stimuli.

“All the time, we are using hidden resources of our brain and doing things we think we are unable to do,” said Beatrice de Gelder, one of the authors.

Gives new meaning to the old saying:  "I see, said the blind man."

—Christie Nicholson

 

For more on blindsight, and this study, please see this 60-Second Science post.

 

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5 Comments

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  1. 1. atarikg 11:41 AM 1/6/09

    Wow,Thanks...

    Reply | Report Abuse | Link to this
  2. 2. Miga 10:12 AM 1/10/09

    Sometimes we really have the ability that we ourselves are unaware of but something that really exist in our mind. It really sounds like the magic, isn't it?

    Reply | Report Abuse | Link to this
  3. 3. happyangel 01:59 AM 1/18/09

    What? This seems sooo weird...
    I thought we have to see in order to navigate something...
    Magic?
    The brain is still a unsolved mystery...

    Reply | Report Abuse | Link to this
  4. 4. happyangel 02:02 AM 1/18/09

    But then again, is it possible that the man has gained/developed some abilities to fill up his inability to see--that's why he can walk without a cane?

    Reply | Report Abuse | Link to this
  5. 5. eco-steve 12:02 PM 2/25/09

    Way back in 1964 our biology master taught us that the eyes not only detect light, but also create the visual images we see. The brain just filters and adjusts the data if necessary. This article would appear to verify this...

    Reply | Report Abuse | Link to this
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