Date: Tue, 02 Dec 2003 14:48:08 -0700

Author: Jerry DiMarco

Subject: Re: seeing colors

Post:

Here is a theory based on the information you provided. If red
sensitive cones illuminated by a red object tire, then maybe their output
is reduced. If their output is reduced, and the other types of cones still
have normal output, would you then "see" the object in its complimentary
color? It sounds like a color addition demo where you decrease one color
and get its compliment in the center (instead of white)...

Jerry


At 03:42 PM 12/2/2003, you wrote:
>A bio teacher here wanted to know why is it when you stare at a red circle
>for 30 s and then look away, you see an image of the circle in its
>complimentary color. I know (think?) there are three types of rods/cones
>on the retina, each being sensitive to a different color. Starring causes
>them to "tire," but why the complimentary-colored afterimage?


<><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

Jerry DiMarco
Manager of Lecture Demonstrations and Instructional Labs
Montana State Univ., Physics Dept.
Bozeman, MT

Our Motto: "There's a demo in there somewhere."
From cablem@wfu.edu Tue Dec 2 16:58:37 2003
Message-ID: <3FCD0AEF.3020401@wfu.edu>
Date: Tue, 02 Dec 2003 16:58:07 -0500
From: Machele Cable
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624
X-Accept-Language: en-us, en
MIME-Version: 1.0
To: tap-l@listproc.appstate.edu
Subject: Re: seeing colors
References: <3FCCFCAE.71E35D51@physics.utah.edu>
In-Reply-To: <3FCCFCAE.71E35D51@physics.utah.edu>
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
X-MailScanner-Information: Please contact the Helpdesk @ 6266 for more information
X-MailScanner-ASU-mta1: Found to be clean
X-MailScanner-SpamCheck: not spam, SpamAssassin (score=0, required 7)
Reply-To: tap-l@listproc.appstate.edu
Sender: owner-tap-l@listproc.appstate.edu
X-Listprocessor-Version: 8.2.10/991025/16:55 -- ListProc(tm) by CREN

Persistance of vision has to do with flickering things, like films. The
red dot issue comes about from this PLUS how the eye/brain processes
light. Light from a red dot actually stimulates the red and blue cones,
the red giving the color, the blue giving the hue saturation,
apparently. So, when we look away, THEN the persistance of vision
happens to make us still see the image. However, the red cone is no
longer stimulated, but the blue cone is stimulated for hue and we see a
blue dot for a moment. I found it on the internet, so it MUST be true! LOL

Interesting info: http://www.handprint.com/HP/WCL/color1.html#ruleshead

Chele


Zigmund J. Peacock wrote:

>Persistence of vision. Zig
>
>Anthony Lapinski wrote:
>
>
>
>>A bio teacher here wanted to know why is it when you stare at a red circle
>>for 30 s and then look away, you see an image of the circle in its
>>complimentary color. I know (think?) there are three types of rods/cones
>>on the retina, each being sensitive to a different color. Starring causes
>>them to "tire," but why the complimentary-colored afterimage?
>>
>>
>
>--
>Zigmund J. Peacock WWW.physics.utah.edu/people/staff/peacock.html
>University of Utah/Physics peacock@physics.utah.edu
>115 SOUTH 1400 EAST #201 Tel 801 581 6602
>SALT LAKE CITY UT 84112-0830 Fax 801 581 4801
>
> "We sleep safely in our beds because rough men stand ready in
>the night to do violence to those who would do us harm"
> -- George Orwell
>
> "All that is necessary for the triumph of evil is that good
>men do nothing!"
> -- Edmund Burke
>
>
>
>
>

--
~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~
Machele Cable Lab Manager Physics WFU
Phone: (336) 758-5532 Fax: (336) 758-6142
~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~
Friends are the Bacon Bits in the salad bowl of life.
~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~ - ~
There's a thin woman inside of me trying to get out,
but I can usually shut her up with some chocolate!

From Paul.Nord@valpo.edu Tue Dec 2 17:16:34 2003
Date: Tue, 2 Dec 2003 16:16:24 -0600
Subject: Re: Simple CAD wanted
Content-Type: text/plain; charset=US-ASCII; format=flowed
Mime-Version: 1.0 (Apple Message framework v553)
Cc: Paul Nord
To: tap-l@listproc.appstate.edu
From: Paul Nord
In-Reply-To: <3FCD0543.89C7A8ED@physics.utah.edu>

Back