Re: Color Visibility

At 12:51 PM 5/20/99 -0400, Bruce Bailey wrote:
>I am quite skeptical of the concept of "voting" as to what colors are
>good/bad for web page visibility.
>
>It seems to me that this would only be useful for hues or combinations that
>were questionable or rendered very differently on different systems.  Even
>then, you would have to do some kind of statistical sample rather than
>volunteer voting.  This kind of hard evidence might be helpful to web
>authors who feel that the "colors looks fine on my screen -- who cares that
>you don't like it".

Thanks for the skepticism Bruce.  We want to make sure we're doing
something valid and also not re-inventing the wheel.  Here's my take on this.

You bring up the comparison of a "statistical sample" as opposed to
"volunteer voting".  As I see it, a web survey is a statistical sample,
albeit one that, at least at first glance, isn't controlled.  But academic
studies usually aren't random statistical samples either.  I was an
experimental psychologist in my student days, and I had subjects in
darkened rooms making judgements which I analyzed via various statistical
tests, like t-tests, ANOVA, regression, etc.  But who were my subjects?
Volunteers, mostly my buddies in the psych department, or people I hired
from the undergrad population.   Looking back, there wasn't a single
presbypopic person in the bunch as I recall. Also there's a tradition in
this area, psychophysics, for the experimenters themselves to be the
observers, as "expert observers".


>I have a hard time believing that no general mainstream usability testing
>and/or research has been done with regard to color
>contrast/visibility/readability.  Surely "expert" opinion has got to count
>for more than how random users "vote".

You're right, there has been mainstream usability testing, and expert
opinion, plenty of it.  I tried to find good info a few years ago.  But I
never find anything that I was comfortable extrapolating to web design.
Sometimes the colors were insufficiently specified.  Sometimes the measure
was reaction time rather than judgements.  Sometimes the stimuli were small
geometric shapes.  Some results were expressed as theoretical equations
that were implausible on their face, e.g. equations that depended only on
the ratio of luminances.

On the other hand, those few years have passed and there may be better
research around.  Or the folks at Smith Kettlewell that Al will be putting
us in contact with may know of something better than what I was able to dig
up.  

Still, thanks for reminding use to double check we're not reinventing the
wheel.

>
>It probably WOULD be meaningful to get real world feedback from users who
>identified themselves as having color blindness.  I have no idea how you
>reach such a population!

Yes, we've got to think about this.

Well, for one thing, approx 10% of males have it to some degree. They may
not know it.   Maybe we should build in a color blindness test... tho it
may be tough to get it to run on screens of unknown characteristics...
hmmm... have to think of that...

There is a classic color blindness test at
http://www.geocities.com/Heartland/8833/coloreye.html

But we're really just concerned with reduced sensitivity to red so we can
do a simpler test.  We'll have to think about that. 


As for more info about existing guidelines and tips about finding subjects:

I posted a request to a color vision mailing list CVNET

http://www.visionscience.com/mail/cvnet/cvnet.info.html

There's a sharware program to tell people who are color blind colors on a
screen
http://hp.vector.co.jp/authors/VA011243/wcolor_e.htm
I'm a bit uncomfortable asking them for their mailing list of registered
users... 

Anyone have further thoughts?

Len







>
>Just my two cents...
>
>Bruce Bailey, DORS Webmaster
>http://www.dors.state.md.us/
>410/554-9211
>
>----------
>From: Chris Ridpath <chris.ridpath@utoronto.ca>
>To: WAI ER IG List <w3c-wai-er-ig@w3.org>
>Subject: Color Visibility
>Date: Tuesday, May 18, 1999 11:56 AM
>
>We've been looking at the problem of trying to determine what colors are
>good/bad for web page visibility. As part of the process, we wanted to set
>up a web site where people could go and 'vote' on several different color
>combinations. In this way we would get some real world results. Our example
>site is at:
>http://aprompt.snow.utoronto.ca/ColorTest.html
>
>Please take a look and let me know your comments.
>
>I also have a small program the tries to determine whether colors are
>good/bad visibility for use in web pages. Let me know if you'd like to have
>a look at it.
>
>Chris
>
>
>
>
>
-------
Leonard R. Kasday, Ph.D.
Universal Design Engineer, Institute on Disabilities/UAP, and
Adjunct Professor, Electrical Engineering
Temple University

Ritter Hall Annex, Room 423, Philadelphia, PA 19122
kasday@acm.org        
(215} 204-2247 (voice)
(800) 750-7428 (TTY)

Received on Thursday, 20 May 1999 17:43:16 UTC