The Naked Scientists

The Naked Scientists Forum

Author Topic: Seen out of the corner of my eye?  (Read 1187 times)

Offline Mazurka

  • Hero Member
  • *****
  • Posts: 510
    • View Profile
Seen out of the corner of my eye?
« on: 16/11/2011 13:19:29 »
I spent this morning watching a (dull) presentation. 

I was sat at an angle to the projector and screen and had an oblique view of the projector.  I could not help but notice that when I glanced at the projector lens,  I would see the red green blue, but if I looked at it I would see white.

No matter how hard I tried, I could only get a momentary glimpse of the red green blue and could not focus on it.

Why is this?



   


 

Offline Bored chemist

  • Neilep Level Member
  • ******
  • Posts: 8644
  • Thanked: 42 times
    • View Profile
Seen out of the corner of my eye?
« Reply #1 on: 16/11/2011 21:32:45 »
The projector gives a red image, then a green one then a blue on in rapid succession. With a quick glance you only see one colour or a blurred multi colour image.
 

Offline Geezer

  • Neilep Level Member
  • ******
  • Posts: 8328
  • "Vive la résistance!"
    • View Profile
Seen out of the corner of my eye?
« Reply #2 on: 17/11/2011 06:04:05 »
It's because your peripheral vision is much better at detecting changes, which is probably an evolutionary advantage. If you look at an old fangled TV with your peripheral vision, you might be able to see it flicker.

Those of us old enough to remember what oscilloscopes were would sometimes take advantage of that technique to observe very faint pulses as they were painted on the CRT screen.
 

Offline Mazurka

  • Hero Member
  • *****
  • Posts: 510
    • View Profile
Seen out of the corner of my eye?
« Reply #3 on: 17/11/2011 10:02:23 »
Thanks.

With a quick glance it was like seeing the light spectrum through a prism but without the orange, yellow, indigo, violet parts and it seemed remarkably sharp (although that could have been an effect of brightness)

I am inclined to agree that it is an effect of peripherhal vision, but I thought that the cones (colour sensitive cells) were concentrated around the fovea "sweet spot" of focuse vision and the rods (monochrome) were more sensitive to movement / low light.
 

The Naked Scientists Forum

Seen out of the corner of my eye?
« Reply #3 on: 17/11/2011 10:02:23 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums