Why Can I See Inside a Cylinder with One Eye Closed?

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In summary, the conversation discusses the phenomenon of seeing different things when covering one eye versus closing it. The participants wonder why they can see inside a cup when closing the covered eye, but not when covering it with an opaque cup. They also question how the brain decides which eye has more control over what is seen. The explanation provided is that when one eye is covered, the photoreceptor cells at the back of the eye are not activated, so the brain fills in the vision with what it has.
  • #1
gabe1scott
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This may be a dumb question but I am curious about it and want to know if anyone can provide me a link or give an explanation to why this is.

If I have a cylinder say like a cup and I put it over one eye I can only see the surroundings with my other eye that is not covered but if I close that eye than I can see inside the cup. Why is this? How does our brain decide which eye has more control over what we see. Why don't I see inside the cup instead?
 
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  • #2
Erm, I can see both. I just put a cup to my right eye and stared straight forward, I could see equally well out of both eyes.
 
  • #3
was the cup opaque though? I am not talking about a see through cup. If the cup surrounding the eye makes it dark where details are barely visible at least in my vision all I see is what my other eye focuses on.
 
  • #4
Ah I see, my cup wasn't opaque but light was coming through the gap. When we cover one eye the photoreceptor cells at the back of the eye no long activate. Rather than show some vision and some blankness the brain fills in the vision with what it has.
 
  • #5
okay thanks for the answer
 

FAQ: Why Can I See Inside a Cylinder with One Eye Closed?

1. Why can I see inside a cylinder with one eye closed?

This phenomenon is known as the "Purkinje effect." It occurs because our eyes have different sensitivities to light and color. When one eye is closed, the other eye adjusts to the dimmer light inside the cylinder, making it easier to see the objects inside.

2. Is this effect only seen with cylinders or can it happen with other shapes?

The Purkinje effect can occur with any object that has a curved surface, such as a cone or a sphere. However, it is most noticeable with cylinders because of their distinct shape.

3. Can everyone experience the Purkinje effect?

Yes, this effect is experienced by everyone with normal vision. However, the degree to which it is noticeable may vary from person to person, depending on individual differences in eye sensitivity.

4. How does the Purkinje effect relate to depth perception?

One of the reasons why we can see inside a cylinder with one eye closed is because our brain uses visual cues to determine depth and distance. The Purkinje effect is one of these cues, along with others such as perspective, overlap, and shadowing.

5. Can the Purkinje effect be used to create optical illusions?

Yes, the Purkinje effect has been used in various optical illusions, such as the "Hollow Face Illusion" and the "Rotating Cylinder Illusion." These illusions take advantage of the differences in eye sensitivity to create a false perception of depth and movement.

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