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.

Join Our Community of Science Lovers!

[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.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


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.

 

60-Second Psych is a weekly podcast. Subscribe to this Podcast:

RSS | iTunes

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe