M
Michael Press
Guest
In article <[email protected]>,
"Pete Biggs"
<[email protected]>
wrote:
> ship wrote:
>
> > But I'm telling you I can SEE that it's red!! And not because I KNOW
> > it's red either.
> > I just tried the experiment again with a white and a red cateye LED
> > light and I shuffled
> > them around and I can still EASILY tell you which is which even in the
> > corner
> > of the eye.
>
> I can't detect colours right at the very edge of my vision, but can when the
> object is moved round a little more. At the edge I can barely make out
> shapes either; just a vague awareness that something is there.
>
> Where does peripheral vision stop and main vision start?
At the margin of the fovea. You might be surprised at
how little we see with our eyes, and how much is
interpreted and interpolated.
Here is the classic paper on the frog eye, What The
Frog's Eye Tells The Frogs Brain. It is a large PDF
file.
<http://jerome.lettvin.info/lettvin/Jerome/WhatTheFrogsEyeTellsTheFrogsBrain.pdf>
The frog eye sees four things.
1) The contrast detector tells, in the smallest area of
all, of the presence of a sharp boundary, moving or
still, with much or little contrast.
2) The convexity detector informs us in a somewhat
larger area whether or not the object has a curved
boundary, if it is darker than the background and
moving on it; it remembers the object when it has
stopped, providing the boundary lies totally within
that area and is sharp; it shows most activity if the
enclosed object moves intermittently with respect to
the background. The memory of the object is abolished
if a shadow obscures the object for a moment.
3) The movement detector tells whether or not there is
a moving boundary in a yet larger area within the
field.
4) The dimming detector tells us how much dimming
occurs in the largest area, weighted by distance from
the center and by how fast it happens.
Note that 2 is a moving insect, 3 is a predator.
Human eyes transmit more than four signals.
One of them is static diagonal stripes.
--
Michael Press
"Pete Biggs"
<[email protected]>
wrote:
> ship wrote:
>
> > But I'm telling you I can SEE that it's red!! And not because I KNOW
> > it's red either.
> > I just tried the experiment again with a white and a red cateye LED
> > light and I shuffled
> > them around and I can still EASILY tell you which is which even in the
> > corner
> > of the eye.
>
> I can't detect colours right at the very edge of my vision, but can when the
> object is moved round a little more. At the edge I can barely make out
> shapes either; just a vague awareness that something is there.
>
> Where does peripheral vision stop and main vision start?
At the margin of the fovea. You might be surprised at
how little we see with our eyes, and how much is
interpreted and interpolated.
Here is the classic paper on the frog eye, What The
Frog's Eye Tells The Frogs Brain. It is a large PDF
file.
<http://jerome.lettvin.info/lettvin/Jerome/WhatTheFrogsEyeTellsTheFrogsBrain.pdf>
The frog eye sees four things.
1) The contrast detector tells, in the smallest area of
all, of the presence of a sharp boundary, moving or
still, with much or little contrast.
2) The convexity detector informs us in a somewhat
larger area whether or not the object has a curved
boundary, if it is darker than the background and
moving on it; it remembers the object when it has
stopped, providing the boundary lies totally within
that area and is sharp; it shows most activity if the
enclosed object moves intermittently with respect to
the background. The memory of the object is abolished
if a shadow obscures the object for a moment.
3) The movement detector tells whether or not there is
a moving boundary in a yet larger area within the
field.
4) The dimming detector tells us how much dimming
occurs in the largest area, weighted by distance from
the center and by how fast it happens.
Note that 2 is a moving insect, 3 is a predator.
Human eyes transmit more than four signals.
One of them is static diagonal stripes.
--
Michael Press