On Wed, 27 Apr 2016 00:19:36 +0100, Johnny B Good wrote:

On Tue, 26 Apr 2016 04:18:26 -0700, whisky-dave wrote:

On Tuesday, 26 April 2016 10:05:49 UTC+1, Mr Macaw wrote:
On Tue, 26 Apr 2016 09:14:27 +0100, dennis@home
wrote:

On 26/04/2016 00:21, Mr Macaw wrote:

Simple experiment. A hula hoop around your head, with a coloured
bead slid slowly round it, while you stare straight ahead. You
shout out the colour when you see it.

That would be a couple of degrees then as rods don't detect colour
only cones do that and they are in the centre of your field of view.
Any colour you see in the peripheral field is just made up by your
brain.

Funny how my eyesight and everyone in the class worked with colour
round there. The only thing you don't pick up colour with is very low
light levels.

you'll have to define seeing and looking.
See if you can read a newspaper out of the corner of your eye. If you
can't youre not really seeing are you?

Most people think their eyes present the full picture, ready formed, as
perceived in their visual cortex when in fact the perceived image is
effectively a virtual reality construct of what your eyes have scanned
during the initial few seconds it took to take in the scene before them
and which continue to refresh and update the scene as you move within and
around the scenery.

In fact, apart from the very narrow angle of high definition[1] offered
by the fovea, most of the near peripheral, out to the periphery provides
low definition 'place marker' information to assist in keeping this
virtual image up to date, assisted by almost unconscious continual
scanning[2] of the scene by the beholder.

The visual cortex complexity represents in excess of 500 million years
worth of evolutionary development. Even so, the visual cortex uses many
shortcuts and 'cheat's to provide timely information of our immediate
environment, shortcuts and 'cheats' that in nature' serve us very well..
However, such 'winging it' methods of visual processing can be readily
demonstrated by testing with artificially created scenes designed to
induce 'optical illusions'.

Just remember that what you think you see is exactly that! It's just
what you *think* you are seeing. The virtual reality machine inside your
head keeps itself so well synchronised with the observed reality around
you that it *is* the reality (well for over 90% of the time in most
circumstances, barring deliberately crafted scenes designed to fool your
visual cortex).

Incidentally, I'm often distracted by the view out of the rear window of
our staircase which is at 90 degrees off axis to my view of the computer
monitor whenever any of our neighbours, during the day, move around their
back garden which backs onto our own back garden whilst I have my
'office' door open. IOW, my peripheral vision seems to be performing as
mother nature intended, a visual perimeter alarm sensor of movement.

[1] To prove how small the effective angle of high acuity is, just
concentrate on the word "visual" in the bottom line of the preceding
paragraph and see, without cheating, if you can actually make out the
last letter of the following word.

Did it, and the next, but not the third word. 19" 4:3 monitor 15 inches from my face. Gap from centre of "visual" to end of "perimeter" = 22mm, gap from centre of "visual" to end of "alarm" = 33.5mm.

[2] One example of such 'unconscious' aspects of scanning a scene is the
automatic blanking out of the jumbled image information reaching the
visual cortex as you cast your gaze between various objects in the scene
before you.

I've felt really confused when I'm lying in bed and see a clock radio LED digital time with one eye, but it's blocked by the pillow with the other eye. The room is dark so my brain doesn't know the pillow is in the way. It can't understand why the clock is only visible with one eye.

If you use an analogue camera and monitor and pan and tilt the camera to
various parts of a scene, you will observe a blurred image on the monitor
during the pan and tilt motions, yet do the same using your eyes to
directly view the scene and such 'blurring' is entirely absent. Indeed it
is simply 'blanked out' or, more accurately, discarded as 'noise' by the
visual cortex.

If I scan round my room, I do see blur if I think about it, but it's usually subconsciously ignored. And usually my gaze will jump quickly from one point to another, so the blur doesn't last long.

That's another amazing thing you can do. Open a book and select a word. Now look around the room, then look back to the same word in the book, you remember precisely where it is and how much movement your head and eyes need to make to get to it. I assume it's like you were saying above, you have a mental image of the whole room, and you're just moving back to concentrate on a known part of it.

--
In the 60's people took acid to make the world weird.
Now the world is weird, people take prozac to make it normal.