Glob or Stick

[Thelonious]

.

[Thelonious]

.

[sunny]

Hey that really makes my brain-mind flash
I am aware of black spots at the intersections in the perifery of my vision yet at the focal point they are always white dot intersections! Perception mmmm.. cant always rely on it, in life to give you all the right answers.

[gidgit]

Far out [img]/infopop/emoticons/icon_cool.gif[/img]

[DLFrost]

<BLOCKQUOTE><font size="-1">quote:</font><HR>Originally posted by sunny:
Hey that really makes my brain-mind flash
I am aware of black spots at the intersections in the perifery of my vision yet at the focal point they are always white dot intersections! Perception mmmm.. cant always rely on it, in life to give you all the right answers.<HR></BLOCKQUOTE>
It's an optical illusion that illustrates a feature of the human visual system--active noise suppression. It some situations (like the above image) it's possible to arrange it so that the noise averaging feature actually generates noise.

Something else interesting about this one... Focus on the center dot and don't move your eyes. As time passes you'll see that the surrounding dots fade out, starting at the outermost ones and working inward. The slightest eye movement resets the effect. (It's easier to see if you turn your head to a 45deg. angle when staring.) This is the noise suppression actually working.

Doug Frost

[Thelonious]

Interesting explanation Doug.

Is this somehow related to the effect that one gets when staring at a fixed point without moving the eyes in the slightest (quite difficult to do) after a while the scene goes dark, then completely black, and everything disappears only to restore at the tiniest eye movement or refocussing.

[DLFrost]

<BLOCKQUOTE><font size="-1">quote:</font><HR>Originally posted by Thelonious:
Interesting explanation Doug.

Is this somehow related to the effect that one gets when staring at a fixed point without moving the eyes in the slightest (quite difficult to do) after a while the scene goes dark, then completely black, and everything disappears only to restore at the tiniest eye movement or refocussing.<HR></BLOCKQUOTE>
Yes, in part. Information in your visual environment which does not change is gradually ignored. This probably helps gets rid of "floaters" and other defects in the visual field.

One of the tricks used in depravation experiments that relates to this was covering the eyes with a set of goggles which provide a smooth, unvarying white field to the eyes. This caused disorientation to the subjects which increased over time. Eventually they started hallucinating as their visual systems just started cranking out content all on their own.

The point of all of this is that your visual system isn't passive like a camera, but is actively involved in constructing what you see.

Doug Frost

[Thelonious]

I see,

Well then Doug, one more question. What the hell are those little amoeba things and other bits that look like a hair under a microsope, than can be seen floating around, if one looks into a bright sky?

It seems they are on the surface of the eye except that they are in focus, which doesn't seem possible. Also they float around too smoothly. It is possible to follow them as if they are floating in ones field of vision. If an observer watches your eyes they will see your iris moving in an extremely smooth manner which under normal circumstances is not possible to do.