The Eyes Have It?

As an oral deaf person I rely a great deal on my eyes.   With my eyesight, I can read lips, facial expressions, hand gestures, and body language  in communications with others.  Many d/Deaf individuals rely on their eye vision for understanding the visual language of ASL, for lipreading/cueing with aided residual hearing or without, and taking in their environment around them.  Many d/Deaf individuals depend on their eyes as a primary sense to take up what their ears don’t do very well and hence, they don’t take their eyesight for granted, the way so many hearing people do.

But ya know, there are some things our eyes don’t see.  Check out http://serendip.brynmawr.edu/bb/blindspot1.html and have some fun.

Yup, we all got our blindspots.

Try the site’s ‘More Blindspots’ tests, such as the “Switching Colors” yellow/green test and the “Lines” test.  The more, the merrier.

As you will discover, our brains make up for the blindspots.  Powerful stuff this gray matter, this brain, our consciousness.

There is a strange phenomenon called blindsight.  It’s been mentioned in a few blogs and on YouTube recently.  Scientific and medical researchers have observed this phenomenon in individuals who suffered brain damage as a result of a stroke, brain surgery or brain trauma.  Blindsight persons “see” (even with 20/20 vision in both eyes) but do not “understand” what exactly they see.  In other words, they can see but don’t have a conscious understanding of what their eyes are seeing.

Blindsight persons are known to “detect” objects as they navigate a room however, only guessing at the shape, color, or movement of an object, but they are unable to actually identify an object for what it is, say a ” bouncing basketball” or a “potted plant” or a “lit lamp”.  They will more likely identify the basketball as some round orange shape moving from left to right, the potted plant as an irregular green shape, the lamp as a round yellow shape.   Theirs is a “residual” vision, but not a conscious one, which in effect makes these persons blind in another way.

Some of you may have seen an example of partial blindsight in someone who has had a stroke for example.   A right-side stroke in the brain can sometimes cause a blindsight of the left eye, hence, the term partial blindsight.  (Right side brain stroke affects the left side of the body, and vice-versa.)  Such a person may be observed eating the food only on the right side of his plate for he can see and consciously understand that side of the plate, leaving the food on the left side of the plate untouched because his left eye doesn’t “understand” what it sees.

Researchers are uncertain about the exact mechanism that causes this blindsight phenomenon.  Some say that it is directly attributed to a damaged visual cortex within the brain that is responsible for conscious seeing.  Others say that the phenomenon is due to the brainstem that, if intact even with a damaged visual cortex, controls basic functions of the body such as the heartbeat and breathing.   The brainstem is the most primitive  part of the brain, site of functions that were critical to prehistoric man’s survival.   So, the basic functions of vision, that is, shape, color, and movement, are believed to be situated in the brainstem as well to serve as a visual alarm system before a threat registers consciously.

So, blindsight is a reminder that a great deal  happens unconsciously on the back burner before an image registers as a conscious thought.

On another note, blindsight reveals (pun intended) that humans with a damaged visual cortex can see without understanding what they see…or that they see.

Now that’s an even weirder thought.

Ann_C

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16 Responses to “The Eyes Have It?”

  1. ireflections09 Says:

    This is my first blog article, so if I’ve made any typo’s, etc. blame it on beginner’s lack of knowledge. 😦

  2. Li-Li's Mom Says:

    Hooray! Have so been looking forward to the day you started blogging!

    On the topic of your first entry, take a look at this link, which takes you to the basketball video from an experiment by Daniel Simons and Christopher Chabris. When viewing the video, try to count the total number of times that the people wearing white pass the basketball. DO NOT count the passes made by the people wearing black.

  3. Candy Says:

    Hey Ann_C, about time you have a blog! Interesting subject and I don’t think I have a blind spot. I tried mapping it. lol

  4. ireflections09 Says:

    Hi Li-Li’s Mom, I viewed your link, interesting! I counted 14 passes with my tired eyes. Thanks for your compliment!

    Candy, lol, if you don’t have any blindspots, you wouldn’t be able to see!

    Take the first test again, look at the crossmark only, NOT the black dot, and move slowly closer to the screen. Don’t look at the black dot, ‘kay? When you get to a certain distance, the black dot will disappear in a kind of “peripheral ” way, you’ll notice it enough. Try the other tests too, remember the same instructions of concentrating only on one motif. It’s fun in a jaw-dropping way at the same time. The one with the pencil test really makes you go OMG.

  5. White Ghost Says:

    Congrats! I’m under the weather!

    Typo? Ha, Obviously, your’e nervous for doing what? Your very first blog.

    If Alabama and Okla (red vs. red) plays against each other at the Bowl Championship Series, you wouldn’t have gotten the blindspot. 😉

  6. Karen Mayes Says:

    Well, well! Hello, I see you got your blog :o)

    Interesting post about blindspots…

    So my eye see certain things but my brain sees them differently?

    Thanks for letting us know…

  7. Dianrez Says:

    That was interesting about blindsight and the experiments on perception. It reminded me of some people bringing a theory that certain deaf people aren’t “visual” learners and by implication, must be auditory learners.

    Would these experiments eventually reveal better ways to teach these people? Or prove that for deaf people, visual is still the preferred way of instruction, with hearing a secondary method?

    Afraid this is going to kick off another controversy…

  8. Candy Says:

    Ok, I tried again. Got it. silly me, eh?

  9. ireflections09 Says:

    WG, lol, red-on-red! Hope you and the weather improve.

    Karen M, The blindspot tests reveal that we do indeed have blindspots. Blindspots occur where the optic nerve from the brain enters the back retinal wall of the eye. There is no retina where the optic nerves are. In reality we should see two small black blindspots (one for each eye) in our vision, but we don’t because our brains fill in the blindspots with the color of the surrounding image. It can even fill in a pattern or a vertical line when there isn’t one over the blindspot. Most of the time we aren’t aware of our brain doing this “filling in” where there is no vision in the blindspots. The tests make you aware of what your brain is indeed doing.

    Ann_C

  10. Mishkazena Says:

    Welcome to the blogsphere, Ann C! 😀

    You picked a great topic to start with.

    Yes, we did an experiment in the labs regarding blindspots. The students found this one a fascinating experience.

    Blindsights can be frustrating, especially for stroke survivors.

  11. ireflections09 Says:

    Dianrez, not looking for a controversy, but your comment reminds me of some research I’ve put off for an upcoming article. Humans also have an auditory cortex in the brain…now you ‘see’ where I’m heading next.

  12. ireflections09 Says:

    Hi MZ, Yes, blindsight is frustrating for stroke survivors and often leave relatives puzzled.

    My F-I-L went thru two brain surgeries, the last one caused blindsight of his left eye. It’s a standing joke at the dinner table when my bro-in-law will interrupt his take of the day to say “Somebody turn W’s plate” and resumes his monologue. 🙂

  13. Li-Li's Mom Says:

    Ann_C, oh my goodness, I can’t believe I left you hanging: 14 passes is great! But you may have missed something … unusual ( I know I did!). It’s called inattentive blindness, and I thought it was a hoax until I watched someone else do the exact same thing.

  14. ireflections09 Says:

    Li-Li’s Mom, actually I did notice the funky gorilla passing thru the first time, but thot one was supposed to count how many passes were being made between those in white shirts. So that’s what I reported, how many passes, but not the gorilla act.

    I do think that many who depend on both sight AND hearing tend to have sensory overload in the brain, when there is a lot going on. Because I don’t rely too much on my residual hearing and more on my eyesight, that may explain why I saw the odd gorilla act in the first place. It did strike me as oddball.

    It seems that the brain can only take so much neural firing and then must filter out some in order for something to sink in the form of a message. Funny though that this video clip didn’t include sound. And many hearing people overlooked the gorilla act? Interesting, this inattentive blindness. Thanks for bringing it up!

  15. Beth Says:

    Right, I think there’s something like a 50% chance that people totally miss the gorilla when they are counting, but everyone sees it when not counting. I was so horrified to realize I’d missed the gorilla entirely, my husband saw it immediately.

    I don’t know that anyone has studied whether deaf people see it more often than hearing people, or if degree of hearing loss comes into play, though. But as you say, it’s fascinating that our brains can filter something as obvious as a gorilla right out of the picture, and opens my eyes to what else we might miss when focusing on one aspect of situation.

  16. Li-Li's Mom Says:

    opps, sorry, I am Beth (Li-Li’s Mom).

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