Another childhood question - about CRT flicker

When I was in high school I asked my optician why can I catch my computer monitor's flickering when looking at it from the corner of my eye, but not when looking at it straight on.
Did this mean that our peripheral vision is better at catching high frequency phenomena than our (more central...? ) vision?

His answer didn't really address the question so I didn't tell him that I started to believe that when people say they think they saw a ghost out of the corners of their eyes, maybe they saw some high frequency phenomena that we can catch with our peripheral vision but not when we look at the thing head on.

(temur's explanation about wave fronts and tail fronts in another thread reminded me of the idea of image residue.)

 

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We see black and white from the edges of the eyeball, and color from the central region. Our night (black and white) vision is better from the edges; i.e. from the 'corner' of the eye. That might have something to do with it.

 

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Wikipedia page says the opposite. Peripheral vision is more sensitive to light, but it has slower response to light. This means looking straight is better at catching fast oscillatory behavior in light intensity.

As for your experience (which I share) there must be some other explanation. I don't think you saw the sweeping of the electron ray on the screen (assuming it was old style CRT monitor), as that would be way too fast. I would argue that the fact that your brain managed to receive this means that the phenomenon was within the "normal" range of frequencies that we can perceive.

 

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Autistic people can sense the CRT flicker more than others. They often have to have a higher refresh rate on their monitors too.

It is well known that peripheral vision is more sensitive. When you want to see something at night you don't look at it directly.

 

Thats not true. Best way to look at\for something is straight on. Sure you may see something out of the corner of your eye but if you want to focus on it you look straight on.

Ghosts in the OP seen from the corners of eyes is probably always due to a vision problem or a vision problem that the person isnt even aware of yet. What they are seeing is the internals of the eye.

 

If you want to see movement in the dark, that is the way.

 

Just because an object does not pass directly in the center of your field of vision does not mean you are seeing the object only because it is in your peripheral or that you are seeing it better.

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Not if what you are looking at is very faint or under low light conditions. There is an old trick astronomers (amateur and pro) use when trying to see a dim object in the night sky with the naked eye. It's called 'averted vision'. You look slightly away from the object (star, nebula, etc.) you want to spot. It pops right out, works great. The b/w receptors in the retina are more sensitive. They are concentrated in the periphery but are less packed there than color receptors are in center of field, so you can see something dimmer but in less detail.

 

But with dim objects I can try to make up an explanation to myself (however flawed): something to do with what part of the eye catches more light...etc.

Being able to see flicker sideways and not at all head on just ....what could that be about? I assumed everyone here would have noticed it (or does everyone have an LCD monitor nowadays?)

I'm starting to wonder now about the comment about having a vision problem.

Wonder if anyone had ever noticed it with the rotating blades of an electric fan as well. I can see the flicker more clearly too when looking at it sideways

 

Most of the time, you just have to know that something is there, not see it clearly.

 

Spidergoat is right. Go outside at night and look up in the sky. Look at a celestial object, such as the Pleiades star cluster. It is one that is comprised of several stars that are a mix of bright and dim. If you look straight at it, it is very hard to see, unless you live somewhere that has very little light pollution. If you look off to the side of it, you can detect it much easier. Also interesting, it is easily photographed, even if you can't see it very well looking directly at it.

I'm not saying I know why that happens, but it is easily testable.

 

Not according to this linky:

http://en.wikipedia.org/wiki/Peripheral_vision

 

Concerning the OP: Is the CRT interlaced?

 

From your link:

Flicker fusion threshold is higher for peripheral than foveal vision. Peripheral vision is good at detecting motion (a feature of rod cells).

 

Wow...you have disproved something that I can go outside and test, and have experienced with a link on the internets.

All of these years a sky gazer, and my experience with looking at dim celestial objects, disproved by Wikipedia.

Apparently data is nothing, unless it is wiki-able.

 

Obviously you scanned over this bit:

Peripheral vision is weaker in humans, compared with other animals, especially at distinguishing color and shape.

But that does explain the question asked in the OP.

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Good work.:thumbsup:

 

Can you use an academic source at least?

 

And even still...if you think about it, is it really that important to detect motion? Seems to me color and shape is more important.:itold:

 

whoa...hey

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:truce:

 

Here is an excerpt from Sky & Telescope; Jul2004, Vol. 108 Issue 1, p82-83, 2p by O'Meara, Stephen James