 Lawrence Hall of Science University of California, Berkeley |
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Re: Color blind Date: Tue, 30 Jan 2001 20:32:53 -0500 From: "Bill Lovegrove" To: "The dome-l mailing list" I am no expert on human vision (any DOME-L's who are feel free to jump in) but I know that there are four different kinds of colorblindness. The most popular theory is that we have three kinds of cones (red, green, blue), one or more of which may be non-functional. In this theory, someone with protanopia has no red-responsive cones and would not perceive red laser light. Someone with one of the other forms might see red but not green. So I don't think switching to a green pointer is the answer for all color blind visitors. Some rare individuals (and some animals like dogs, apparently) have no functioning cones at all and so have monochromatic vision. There is a range of colors the rods respond to which probably varies in different animals. I think the human rod response includes red, so a person with monochromatic vision (and your dog) can see the laser light, it just doesn't look "red" as distinguished from any other color. For a brief intro to the subject, look up "Colour vision" at http://www.britannica.com/.
I use a red laser pointer like most of you but I have been thinking of looking for a good old-fashioned white arrow alternative. Bill Lovegrove |
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