Half of us may be able to see without light
"What I saw was a blur," study participant Lindsay Bronnenkant said. "It was almost like I was looking at a light source."
October 31st, 2013
12:04 PM ET

Half of us may be able to see without light

Wave your hand slowly in front of your face.

Did your eyes track the movement? If so, your brain has formed a memory of that action; it will remember what the motion looks like in case you ever do it again.

In fact, a new study suggests that even if you wave your hand in front of your face in total darkness, your eyes may "see" it simply because they've seen it before.

"One thing our brains are exceptionally good at is picking up on reliable patterns," said lead study author Duje Tadin, professor of cognitive sciences at the University of Rochester. "Think about how many times you moved your hand and saw that movement ... It makes sense that our brains exploit this strong link."

Tadin and his colleagues conducted five experiments involving a total of 129 people. Their results were published online this week in the journal Psychological Science.

The blindfolds

For the first two experiments, participants were shown two blindfolds. They were told that one of the blindfolds "may allow a small amount of light to pass through." In reality, both blindfolds blocked all light.

In other words, participants were led to expect NOT to see with one blindfold, and to expect to MAYBE see something with the other. This produced something called "experimentally controlled expectations" so researchers could collect data in a less subjective atmosphere.

Participants were asked to wave a hand over their eyes at a slow, comfortable pace while wearing one of the two blindfolds. Researchers then asked them whether they saw anything, and if they did, what they saw.

In the first experiment, participants were told both blindfolds would be used, so they expected to potentially see in one of the two trials.  In the second experiment, participants were told they had a 50/50 chance of getting the "seeing" blindfold each time.

About 50% of the participants reported experiencing some visual sensation in the first two experiments, despite being completely blindfolded; a few described well-defined forms in the darkness. Others confidently reported not seeing anything at all.

The researchers concluded that kinesthesis, or movement in your limbs, can actually generate visual sensations - but it's a learned ability.

"Our brain predicts what we are about to see and generates an image accordingly," Tadin said.

I can't see you

In the third experiment, the researcher waved his or her hand in front of the participant's face while they were blindfolded.

In the first trial, no one reported seeing the researcher's hand. In the second, only two of 16 participants reported seeing movement.

This supported the researchers' theory that you can only "see" your own body motion because your brain has so many reliable memories of its own limbs.

The super seers

In the fourth experiment, a select group of users with synesthesia replicated the first experiment. People with synesthesia experience a rare blending of the senses; some see colors when they read, others experience tastes when they speak certain phrases or words.

"What we initially discovered was a blending of the senses - our subjects had visual sensations that were caused by another sense," Tadin said. "We hypothesized that this ability to see your own hand in darkness would be stronger in synesthetes."

The synesthetes' (people who experience synesthesia) results were "literally off the chart," Tadin said; they all reported very vivid sensations of seeing their hand in motion while blindfolded.

More objective data

In the fifth experiment, researchers removed the blindfolds and placed participants in total darkness with a head-mounted eye tracker. The machine recorded their eye movement as they first waved their own hand in front of their face, then had a researcher wave his/her hand, and then waved a cardboard cutout of a hand.

This experiment provided objective evidence to back up the other experiments' findings. People who reported seeing their hand had eye movements that were twice as smooth as those who did not.

"We can only generate smooth following eye movements if we have a moving target to lock on," Tadin explained. "We had one synesthete that had perfectly smooth eye movements when following her hand in total darkness.  For her, we really thought we made a mistake and left the lights on."


This doesn't mean that humans are preprogrammed to see in the dark.  It's learned, Tadin said, and likely only applies to our own body movement.

Tadin and his colleagues hope this research can one day be used to improve hand-eye coordination. They are currently working on this idea with a group of older adults, a population that often experiences hand-eye coordination difficulties.

soundoff (33 Responses)
  1. nodat1

    see without light what line would James Brown have in the Blues Brothers ??????

    October 31, 2013 at 13:57 | Report abuse | Reply
    • Solomon

      So one day I was walking on the sidewalk and I could see perfectly clear!

      November 6, 2013 at 15:27 | Report abuse |
  2. Howard

    Does your brain really see your hand moving in the dark? Or is it more likely that your brain formed a memory of the sight of your moving hand AND THE PHYSICAL SENSATION OF THE HAND AND ARM (THAT'S CONNECTED TO THE BRAIN, TOO)? Then, when you move your hand in the dark, the brain's memory of the physical sensation of the movement also recalls the "vision" that corresponds to that movement?

    October 31, 2013 at 15:27 | Report abuse | Reply
    • everything in Moderation

      That's exactly what the researchers said.

      November 1, 2013 at 09:24 | Report abuse |
  3. Dexter

    I just took your advice JC, thank you very much, I needed that... I can see clearly now.

    October 31, 2013 at 17:00 | Report abuse | Reply
  4. are122

    I'm amazed your brain dismisses stuff you see. New lens in eye I could see the semi circle of it. Really annoying but doc said in time (2 – 3 weeks) your brain would dismiss it from sight. It did. I doubt if dogs see their long noses.

    November 1, 2013 at 00:30 | Report abuse | Reply
  5. cfh

    It also strikes me ( no JC, not your test) this might be a technique to identify synesthetes that are so marginal they don't recognize their ability. Thus to improve such talent. And yes it IS a (an) important and useful talent.

    November 1, 2013 at 00:35 | Report abuse | Reply
  6. BrotherCavil

    "Attention grabbing headline misleads!"

    November 1, 2013 at 01:11 | Report abuse | Reply
  7. SixDegrees

    Wow. You mean we have a mental model of our body and its relation to the environment inside our heads? What earth-shattering, shocking news.

    And here, I've thought all along that's what we called "experience".

    November 1, 2013 at 05:49 | Report abuse | Reply
  8. T.Storm

    As a cave diver & been nearly 2000 ft away from any entrance, lights out, I have been in total, absolute darkness before. It is a darkness that your eyes can not adjust to. Yes, your mind can imagine what is going on in front of it,.. but no, in that kind of darkness, you can not physically see anything.

    November 1, 2013 at 09:46 | Report abuse | Reply
  9. JM

    "Half of us might be able to see without light" uh, sure. That headline fits great with the article. Here's a statistic: half of all journalists have melted their brains with dangerous drugs and alcohol and now can't tell the difference between fact and fiction.

    November 1, 2013 at 10:05 | Report abuse | Reply
    • JGN

      And another interesting statistic is that, of that half group of partially brain dead journalists, 85% work for Fox and 15% work for CNN but the 15% write 69% of all the articles.

      November 5, 2013 at 10:27 | Report abuse |
  10. gr4vyb0at

    So.... this has absolutely nothing to do with seeing in the dark and everything to do with the placebo effect. -_- Sweet headline.

    November 1, 2013 at 10:30 | Report abuse | Reply
  11. Boomer in Mo

    That explains a lot about my family. My husband swears we are half-bats because we walk around in the dark, inside and out, and we can see and he can't. I walk every morning and this time of year it is 1-2 hours before the sun comes up. I take a flashlight but only use it when I'm in the road and a vehicle is coming to let the driver know I and my dog are there. As soon as they pass, I turn it off because I actually can see better by starlight than by flashlight. Weird I know

    November 1, 2013 at 11:37 | Report abuse | Reply
  12. cali girl

    When I drive the regular paths to and from work, I know exactly when a bump in the road is upon me. It as if I have memorized the road. Seems that seeing in the dark could also be related to learning what is around our environment.

    November 1, 2013 at 19:15 | Report abuse | Reply
  13. Ben

    As Vin Deisel would say "You're not afraid of the dark are you?"

    November 2, 2013 at 13:54 | Report abuse | Reply
  14. Mitch Vansen

    I just got paid $5628 working off my laptop this month. And if you think that's cool, my divorced friend has twin toddlers and made over $8.1k her first month. It feels so good making so much money when other people have to work for so much less. This is what I do, Best96DotCom

    November 3, 2013 at 11:57 | Report abuse | Reply
  15. Trogloxene

    This seems like common sense to me because, obviously, every single sensation and perception we experience exists nowhere except in the brain. But try going into a cave and getting around. I guarantee zero percent of people can see in the dark.

    November 5, 2013 at 16:46 | Report abuse | Reply
  16. Dr. Michele Ross

    There are three kinds of cells in the retina that help with vision: rods, cones & a new type of cell that contains melanopsin. Even blind people, who lack rods and cones but have this third type of cell, can see some things in complete darkness because these cells sense irradiance. While not discussed in this CNN articles, presence of more melanopsin-containing cells in people with synesthesia could be a possibility for why they hand see their hands in the dark.

    November 7, 2013 at 06:32 | Report abuse | Reply
    • allenwoll

      Garbage ! ! . "Irradiance" IS light, just not light within the traditional frequency limits for "visible light".
      What is your opinion on the value of snake oil in medicine ? ? . Have you ever attended a course in Physics ? ? ?

      November 24, 2013 at 01:40 | Report abuse |
    • jcat

      Light is irradiance. If melanopsin senses irradiance, then seeing with the cones/rods that sense irradiance is *not* seeing without light.

      November 25, 2013 at 16:44 | Report abuse |
  17. jcat

    This is an unfortunate example of journalistic malpractice - an attention-grabbing headline that confuses people, and is not adequately explained inside the story. Real seeing without light would be if the subjects eyes tracked the researcher's hand (or the carbon cutout hand) as it moved in front of their eyes.

    November 25, 2013 at 16:48 | Report abuse | Reply
  18. Michaelendut

    wh0cd150509 metformin 500mg tablets generic for robaxin

    August 29, 2017 at 18:04 | Report abuse | Reply
  19. Michaelendut

    wh0cd812726 revia amoxil clonidine

    August 30, 2017 at 06:35 | Report abuse | Reply
  20. nike mercurial galaxy

    "Hes 35, has won the lot and still he wants to play at Northampton."
    nike mercurial galaxy http://foot.secretariat-alc.fr/Nike-Mercurial-Superfly-FG-Noir-Nike-Mercurial-Galaxy-IR5080.html

    September 1, 2017 at 03:41 | Report abuse | Reply
  21. エルメス コピー


    October 11, 2017 at 23:55 | Report abuse | Reply
  22. Eldora Monceaux

    Can I say that of a relief to discover someone that really knows what theyre talking about on the internet. You actually realize how to bring a worry to light and earn it critical. Lots more people must read this and understand this side of your story. I cant think youre less well-known since you also definitely hold the gift.


    January 12, 2021 at 00:56 | Report abuse | Reply
  23. Chester Shaff

    Simply wanna remark on few general things, The website design is perfect, the content material is rattling superb : D.


    January 15, 2021 at 20:17 | Report abuse | Reply
  24. Jarrett Berrocal

    Hello There. I found your blog using msn. This is a really well written article.I’ll be sure to bookmark it and come back to read more of your useful info. Thanks for the post.I will definitely return.


    January 18, 2021 at 13:20 | Report abuse | Reply
  25. Taylor Fujimoto


    January 21, 2021 at 11:12 | Report abuse | Reply
  26. Holly

    Very well worded!


    March 4, 2021 at 18:32 | Report abuse | Reply

Post a comment


CNN welcomes a lively and courteous discussion as long as you follow the Rules of Conduct set forth in our Terms of Service. Comments are not pre-screened before they post. You agree that anything you post may be used, along with your name and profile picture, in accordance with our Privacy Policy and the license you have granted pursuant to our Terms of Service.

About this blog

Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.