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Why Can't Some People See Magic Eye Pictures?

When we discussed how Magic Eye pictures work, a lot of people commented about how they can never see the hidden image. So what gives? Is there something wrong with these people's eyes? Are they cursed? Are there really no hidden pictures? Is this all a hoax?

Most Magic Eye problems have to do with the way the eyes work with each other and the brain. To view 3D stereo images, your peepers have to work together as a coordinated team. If they're not pulling together, you're going to have some glitches in your binocular (two-eyed) vision or stereo vision (where the two slightly different views from your eyes are combined in the brain). A number of things can cause binocular and stereo vision impairment — most commonly, deviations or misalignments of one or both eyes ("crossed eyes" or "wall eyes"), situations where one eye is dominant because visual stimulation either transmits poorly or not at all from the other, astigmatism or cataracts. If you think you have an eye problem, go see an eye doctor who can test and treat your stereo vision.

If your eyes are fine, then your Magic Eye problems could just be a matter of technique. The makers of Magic Eye offer this advice:

Hold the center of the printed image right up to your nose. It should be blurry. Focus as though you are looking through the image into the distance. Very slowly move the image away from your face until the two squares above the image turn into three squares. If you see four squares, move the image farther away from your face until you see three squares. If you see one or two squares, start over!

When you clearly see three squares, hold the page still, and the hidden image will magically appear. Once you perceive the hidden image and depth, you can look around the entire 3D image. The longer you look, the clearer the illusion becomes. The farther away you hold the page, the deeper it becomes. Good Luck!

[Special thanks to my friend Molly, who can't see 3D movies and encouraged me to steal her story idea for a Big Question.]

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Big Questions
What Is the Difference Between Generic and Name Brand Ibuprofen?
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What is the difference between generic ibuprofen vs. name brands?

Yali Friedman:

I just published a paper that answers this question: Are Generic Drugs Less Safe than their Branded Equivalents?

Here’s the tl;dr version:

Generic drugs are versions of drugs made by companies other than the company which originally developed the drug.

To gain FDA approval, a generic drug must:

  • Contain the same active ingredients as the innovator drug (inactive ingredients may vary)
  • Be identical in strength, dosage form, and route of administration
  • Have the same use indications
  • Be bioequivalent
  • Meet the same batch requirements for identity, strength, purity, and quality
  • Be manufactured under the same strict standards of FDA's good manufacturing practice regulations required for innovator products

I hope you found this answer useful. Feel free to reach out at www.thinkbiotech.com. For more on generic drugs, you can see our resources and whitepapers at Pharmaceutical strategic guidance and whitepapers

This post originally appeared on Quora. Click here to view.

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Big Questions
Do Cats Fart?
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Certain philosophical questions can invade even the most disciplined of minds. Do aliens exist? Can a soul ever be measured? Do cats fart?

While the latter may not have weighed heavily on some of history’s great brains, it’s certainly no less deserving of an answer. And in contrast to existential queries, there’s a pretty definitive response: Yes, they do. We just don’t really hear it.

According to veterinarians who have realized their job sometimes involves answering inane questions about animals passing gas, cats have all the biological hardware necessary for a fart: a gastrointestinal system and an anus. When excess air builds up as a result of gulping breaths or gut bacteria, a pungent cloud will be released from their rear ends. Smell a kitten’s butt sometime and you’ll walk away convinced that cats fart.

The discretion, or lack of audible farts, is probably due to the fact that cats don’t gulp their food like dogs do, leading to less air accumulating in their digestive tract.

So, yes, cats do fart. But they do it with the same grace and stealth they use to approach everything else. Think about that the next time you blame the dog.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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