The human eye has a blind spot

illustration-blind-spot.gif

The human eye has a blind spot at the area of the retina where the optic nerve leads back into the brain. [via]

The blind spots in each eye are aligned symmetrically so that most of the time, one eye’s field of vision will compensate for the loss of vision in the other. The diagram above shows where the blind spots are located.

To find the eye’s blind spot, you can do the following tests.

In order to find the blind spot of the right eye, it is necessary to close the left eye, focus the right eye on a single point, and see if anything vanishes from vision some 20 degrees right of this point. The following diagram has a set of characters on the left hand side, and black circle on the right. Keeping your head motionless, with the right eye about 3 or 4 times as far from the page as the length of the red line, look at each character in turn, until the black circle vanishes.

right-eye-blind-test.gif

This is seriously some trippy stuff!

The opposite idea works in testing the blind spot of the left eye as well. Just do the exact same as the image above, but with the left eye opened and the right eye closed.

left-eye-blind-test.gif

Those are the two basic eye tests. They worked for me and now I know for sure that the blind spot in the human eye is real. This Blind Spot page has more tests that you can do.

It’s amazing how the brain assumes certain things in our field of vision so accurately despite the fact that the eyes cannot actually see what is there.

THIS IS THE COOLEST THING I’VE LEARNED ALL WEEK!

Permalink Comments (20)

20 Responses to The human eye has a blind spot

  1. mun says:

    a friend told me that girls have more peripheral vision than boys do.
    i don’t know if it’s true or not but in order for that circle to vanish, i had to look a little farther away than where the letters are.

  2. Doobybrain says:

    RE: mun
    but isn’t it neat that it still works?!

  3. yun says:

    Whoa, weird.

  4. Joel Liu says:

    RE: Mun

    So you think you better than us!?

  5. becca says:

    RE: Joel
    HAHAHAHA!

    with my right eye.. the dot disappeared when i was at the “cks” line.. and with my left eye it disappeared when i was at the “dlt” line.. so does that mean my left eye is stronger?

  6. mun says:

    whoa! so this morning when i tried it, i had glasses on and i had to look farther to see when the circle vanished. and i just tried it again with my contacts on and it disappeared with the letters! whoa! WHOA!

  7. karena says:

    That’s so cool! I feel like my eyes are broken now though. It’s no longer whole like I thought it was. haha

  8. bobs your uncle says:

    wooh

  9. Stevie Wonder says:

    …I still don’t see the point of this

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  12. JUSTWONDERING curiosity :) says:

    Does being left handed affect the blind spot? would you have to close different eyes if you were left handed? please answer my question!

  13. Andyfalc says:

    The distance from the letters is critical if you are comparing your eyes. The experiment can be simplified into:

    X X

    Close or cover one look at the X directly in front of the open eye and increase or decrease the distance until the X at an angle to the open eye disappears…

  14. Andyfalc says:

    In my previous post the Xs should have been about 8 to 10 cm apart.
    It is strange to think there is definitely information missing from our stereoscopic reflected light simulation and we don’t notice………..

  15. JOHNNY WALKER says:

    iT’S tHE cREATION sTUPID!

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