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Peter Creasey
November 1st, 2005, 02:02 PM
This is Quite an Illusion (http://www.patmedia.net/marklevinson/cool/cool_illusion.html)

Any explanations???

Mike Landi
November 1st, 2005, 03:58 PM
This is Quite an Illusion (http://www.patmedia.net/marklevinson/cool/cool_illusion.html)

Any explanations???

It has a lot to do with how the human eye works. The cells in your retina register color by the energy of the light waves striking the cell. Blue has more than red so blue triggers a different reaction in the cells (the "cones") than red.

There are limits. The one you are seeing here is the flashing of colored dots that have non-sharp edges cause the cells in your eye to 'concentrate' (for lack of a better term) and they do not get a chance to rest. What happens is that the color active pigments in the cells get diminished. The cells to not 'recycle' properly and a false message is sent (the green). After a while, the cells tire and cannot respond fast enough. That causes the dots to vanish. Your brain gets confused and fills in the 'missing' pieces of the image.

(Note: I'm no biologist so I'll defer to anyone who knows more than I remember from school. <g>)

Judy G. Russell
November 1st, 2005, 04:04 PM
Oooh... that one's nice... but it doesn't work exactly in Firefox. (At least not set up with the security and image controls the way I have it.)

Judy G. Russell
November 1st, 2005, 04:05 PM
Interestingly, with Firefox set up the way I have it, there's no moving pink dot and therefore no green dot at all. But the pink ones disappear anyway if you stare at the plus sign.

Peter Creasey
November 1st, 2005, 04:26 PM
it doesn't work exactly in Firefox.

Judy, I wonder if the results you observe have more to do with how your eyes are viewing things rather than your Firefox settings.

Peter Creasey
November 1st, 2005, 04:29 PM
I'll defer to anyone who knows more than I remember

Mike, Your explanation is impressive.

Since posting the illusion link, I have learned that it is a textbook Troxler Effect.

Lindsey
November 1st, 2005, 04:46 PM
What happens is that the color active pigments in the cells get diminished. The cells to not 'recycle' properly and a false message is sent (the green).
That sounds like the same phenomenon that is at work when you stare at a fixed image for a long time and then when you look away at a white wall, you see an image that is the negative of what you were staring at.

The rest of your explanation sounds very good to me, but I haven't had biology since high school, and only 1 year of introductory psychology in college. And all of that was longer ago than I like to admit...

--Lindsey

Lindsey
November 1st, 2005, 04:48 PM
Oooh... that one's nice... but it doesn't work exactly in Firefox. (At least not set up with the security and image controls the way I have it.)
Works for me in Mozilla, but I may not have the same security settings you have.

--Lindsey

Lindsey
November 1st, 2005, 05:11 PM
Since posting the illusion link, I have learned that it is a textbook Troxler Effect.
Uh-oh, I just had a thought...

Admit it: Ralph put you up to this, didn't he? This is some sort of hypnotic thing to pull us all into the VRWC, isn't it?

Yikes!!!!!

--Lindsey

Gary Maltzen
November 1st, 2005, 06:15 PM
Any explanations???
Vision of color is somewhat relative. Years ago my cousin described to me a Kodak experiment with two-color projection systems (as opposed to Red-Green-Blue) where they found that viewers would see a color that wasn't present simply because there was so much of it's counterpart. A white dot on a magenta screen will appear to have a greenish hue.

Karl Semper
November 1st, 2005, 06:20 PM
Judy,

I had to allow animation in Firefox for it to work. Since I use PrefBar, that is an option that I can easily enable or disable. With animation enabled it works as described.

Karl

Mike Landi
November 1st, 2005, 06:40 PM
That sounds like the same phenomenon that is at work when you stare at a fixed image for a long time and then when you look away at a white wall, you see an image that is the negative of what you were staring at.

I think it is the same principle, but it has been a long time. <g>

Judy G. Russell
November 1st, 2005, 07:17 PM
Admit it: Ralph put you up to this, didn't he? This is some sort of hypnotic thing to pull us all into the VRWC, isn't it?ROFL!!! That's just the sort of thing he would do, isn't it???

Judy G. Russell
November 1st, 2005, 07:18 PM
But would Troxler's effect (when an observer fixates on a point in central vision and attends to a peripheral stationary stimulus, the peripheral stimulus eventually fades from awareness) explain the green dot?

Judy G. Russell
November 1st, 2005, 07:19 PM
Judy, I wonder if the results you observe have more to do with how your eyes are viewing things rather than your Firefox settings.Nope. It has to do with the fact that I have animation turned off in Firefox.

Judy G. Russell
November 1st, 2005, 07:19 PM
It's an image setting (I turn off animations) rather than security.

Judy G. Russell
November 1st, 2005, 07:20 PM
That's it, Karl: I have animations turned off. Thanks.

Lindsey
November 2nd, 2005, 01:11 AM
It's an image setting (I turn off animations) rather than security.
Software these days comes with WAY too many options--but turning off animations sounds like a very useful one!

--Lindsey

Peter Creasey
November 2nd, 2005, 08:34 AM
But would Troxler's effect (when an observer fixates on a point in central vision and attends to a peripheral stationary stimulus, the peripheral stimulus eventually fades from awareness) explain the green dot?

Sorry, Judy, while I've done some cursory reading about Troxler Effect (after learning about it yesterday), I have no idea what the answer might be to your question.

Judy G. Russell
November 2nd, 2005, 09:06 AM
Software these days comes with WAY too many options--but turning off animations sounds like a very useful one!In Mozilla, Edit | Preferences | Privacy & Security | Images, right side on the bottom. I usually leave it set at "Once".

Judy G. Russell
November 2nd, 2005, 09:08 AM
Sigh... where's an experimental psychologist - opthamologist when you need one?

RayB (France)
November 2nd, 2005, 10:20 AM
But would Troxler's effect (when an observer fixates on a point in central vision and attends to a peripheral stationary stimulus, the peripheral stimulus eventually fades from awareness) explain the green dot?

Here is a bit to add to this optical confusion. If you are looking for something in extremely low light (dark or almost dark), you can only see it by not looking directly at it.

Judy G. Russell
November 2nd, 2005, 10:23 AM
Here is a bit to add to this optical confusion. If you are looking for something in extremely low light (dark or almost dark), you can only see it by not looking directly at it.Because you're seeing it better with peripheral vision? Or rods or cones or some such?

Karl Semper
November 2nd, 2005, 11:00 AM
I have them turned off by default and only turn them on when I want to see someting animated.

Judy G. Russell
November 2nd, 2005, 01:25 PM
That's one of the things PrefBar (http://prefbar.mozdev.org/) is really good for!

Lindsey
November 2nd, 2005, 07:21 PM
In Mozilla, Edit | Preferences | Privacy & Security | Images, right side on the bottom. I usually leave it set at "Once".
Aha! Thanks--I will have to try that; some newspaper web sites are driving me nuts with wiggly ads.

--Lindsey

Lindsey
November 2nd, 2005, 07:31 PM
Because you're seeing it better with peripheral vision? Or rods or cones or some such?
The latter--I do remember that much from Psych 101. The cells that are most receptive to low light (rods, as it turns out, but I had to look it up) are concentrated around the periphery of the retina, not in the center. Rods detect movement and shades of gray and don't require much light to function; cones detect colors, and they need bright light to function fully.

--Lindsey

Judy G. Russell
November 2nd, 2005, 09:50 PM
Glad to help.

Judy G. Russell
November 2nd, 2005, 09:51 PM
I'm surprised I even remembered that the different cells were called rods and cones. Then again I'm surprised I remember what I had for breakfast...