[Psych3120] (no subject)

[Kristin Ward]

We'll actually be looking at Color Vision (and color blindness along with it) later in the semester.  The color vision section in the online readings discusses color deficiencies.

To sum it up, here's the 30-second version of color deficiencies:

Color blindness is more usually a color deficiency; that is, the individual can still perceive some color, but has trouble with a particular wavelength of color.  People who have the most common type of color blindness (anomolous trichromats) possess the usual three types of cones (red, green, and blue), but one set of these has an abnormal absorption spectrum. If one set of cones has an abnormal absorption spectrum, the system will still function, but the individual will have difficulty perceiving colors normally handled by that set of cones (for example, a person who's red cones had an abnormal absorption spectrum would have difficulties perceiving red)

Other, less common, types of colorblindness occur when one of the types of cones is missing altogether.  The individual will still have the normal number of cones, but they will only have one or two of the types of cones.  A dichromat has two of the cone types and a monochromat has only one.  (For example, a dichromat might possess only green and blue cones and be missing red cones and a monochromat might have only green cones and be missing blue and red).

Kristin

> I have taken a few classes that have discussed color blindness so I will try
> to offer what I know.  
> 
> In the eye there are the cones and rods.  The cones are what is responsible
> for color vision.  Furthermore, there are three types of cones each with a
> different pigment.  These pigments allow different cones to respond to
> different wavelengths of light.  For example, there is a red, green and I
> think a blue pigment.  These pigments either excite or inhibit the ganglion
> nerves and allow us to see the spectrum of colors.  Now when there is a
> genetic defect in the pigments it can result in color blindness.  Therefore,
> Your dad probably has a defect in the gene that encodes for the red pigment
> that would allow him to see the color, but not defective with respect to the
> blue pigment which is involved with seeing yellow.  Thus, people who are
> color blind most deffinitly have cones within the fovea, however, some of
> them are defective due to their faulty pigments.  With respect to color
> blindness coming from the mothers side, The gene for color blindness is
> probably an X linked gene which would make it more prevelent in males.  I am
> not sure if it is exclusive to males though.  I think that because males
> only have one X chromosome that it probably is just much more frequent in
> males than in females.  
> 
> 
> 
> On Thu, 31 Aug 2000 12:58:38 -0600 (MDT), psych3120@lists.csbs.utah.edu
> wrote:
> 
> >  My dad is colorblind.  He can see yellow but not red, which makes it
> >  difficult at traffic stoplights.  In the lecture on Tuesday, we discussed
> >  the opponent process and the color circle.  I was wondering, if people
> >  with color vision get the color circle, what do people who are colorblind
> >  have and why are they able to see some colors but not others?  I was also
> >  wondering, do people who are colorblind have any cones in the fovea?  I
> >  heard that colorblindness is due to heredity from the mother and that
> only 
> >  males get it.  Is this true?
> >  Amy Cahoon 00077943
> >  
> >  
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