According to estimates from the Howard Hughes Medical Institute, somewhere around 7% of men and 0.4% of women are color blind. The most common is red-green color blindness. I always wondered whether the presentation rule of “never use red” in a presentation was true. So, I spent the a few hours on the website www.vischeck.com to find out.
Vischeck.com lets you upload images to see how they would appear with different types of color blindness.
So, we can’t tell yellows from reds and greens, but we can still see the BOLD effect in the words clearly.
I decided to try a few of my own slides to see how they project:
These first two are from a lecture I developed before abandoning red altogether. I was very disappointed to find out my orange (2nd pic) suffered the same fate as red.
Here is the effect in some of my more recent slides.
So, the morale of the story is that it is likely better to just avoid red altogether, as well as green. However, they can be used with the following caveats:
- Do not try to contrast reds, yellows, and greens because they all look the same
- Consider using bold, italics, or other effects to give emphasis in addition to the color
- Used in isolation, a red or a green will appear yellow to a small portion of your audience. It will still stand out, just not the way you intended
- Checking your slides at a site like www.vischeck.com will avoid creating presentations that inadvertently diminish the learning of a portion of your audience
Howard Hughes Medical Institute (2005). Seeing, Hearing, and Smelling the World/Breaking the Code of Color: Color Blindness: More Prevalent Among Males. http://www.hhmi.org/senses/b130.html