Our eyes are attracted to shiny things. You know that when you take a walk in the park; the glint of the sun from a gum wrapper lying in the grass draws your attention. Or you look up at the sky on a clear, moonlit night - that big white orb is what catches your eye. Even the stars play second banana to the brilliance of the moon. Our eyes are attracted to light.
And yet in a presentation situation, many of us put black text on white screens. I want you to think for a moment about what that's doing to the audience. It's been described as trying to read the lettering on a switched-on light bulb. After a while, it makes the audience stare back at us like "deer caught in the headlights." To a presenter, this is referred to as "white death."
Since the object of attention is letters (not the background), it seems to make more sense to make those objects white. In other words, support graphics and text should be placed on a dark background.
My extensive experience in television supports this hypothesis. But I wanted more concrete support. I searched the internet for additional information and studies on the subject. Here's what I found:
Our eyes are naturally attracted to light.
Light waves enter the eye through the pupil and strike the back of the eye, called the retina. The retina is lined with a series of light sensing cells known as cones and rods. When they get hit with light, a chemical reaction occurs which sends electrical impulses to the brain. The brighter the light (for example, white), the more intense the electrical impulses. The brain then interprets the intensity and in this case, tells us the light is "white." No light, no stimulus.
So, by using black text on a white screen, you're actually asking your audience to read what they don't see! Our brains have to calculate the dimensions of the area that doesn't reflect light and turn that into meaningful information. That's additional work the brain has to do to understand the black text.
Meanwhile, a highly reflective screen blasted with white light is continually stimulating the cones and rods in our eyes. Over time, it will start to hurt your audience's eyes and decrease their concentration. You don't want to make it any more difficult than necessary for them to absorb your message!
White light "bleeds."
Black letters on a white background are affected by adjacent, projected, white light. The letters appear to become thinner. That's because the bright, white light "bleeds" onto them. They aren't actually thinner. However, they appear to be thinner. That makes them harder to decipher, or read.
The other effect of a white screen on small, black text is that is reduces the desired contrast. The black letters are somewhat overpowered by the reflected light and actually become dark or medium grey. The smaller the letters, the more pronounced the effect.
On the other hand, when you reverse out type (make it white on a dark background), the very opposite happens and the white type appears bolder. On top of that, white type optically appears closer to us (above the black background). This is the effect you want to create as a presenter. It makes it easier to see the white text.
Projected (reflective) light is different than ambient light.
You might say to me, "But we've been reading black text on white pages for centuries." That's true. But print and paper create a different environment than light projected on a screen, for two key reasons:
Firstly, ink is absorbed by paper. If printing is not well done, you'll end up with thinner letters, which in some cases, can completely "drop out." To compensate, good designers pick a stronger typeface. And with a solid application of ink, the letters will slightly bleed into the white area, making them stronger and easier to read.
If you try to reverse the ink (print white letters on black), the opposite happens. What you're actually doing is printing black everywhere but where the letters are. The letters will get thinner due to the bleed (the absorption of the ink by the paper), plus you will use more ink, making the printing process much more expensive.
Secondly, printed pages are read in ambient light – not in projected or reflected light. This is not a high contrast situation (like a computer screen or projected image on stage). Therefore the contrast is at an acceptable level. The white of the page is not being reflected back into our eyes.
Traditional computer screens project light in a similar manner to projectors used in a boardroom setting. Any white light is beamed into the eyes of the viewer. It creates a high contrast situation.
Don't let the screen overpower you!
Here's yet another reason not to use white backgrounds. Think of a screen on stage in a theatre . . .
In theatre, we take great pains to light the actors properly so that they are the focal point of any dialogue or action. The same thing holds true in television.
If you're a presenter and properly lit, projecting white light onto a reflective screen anywhere on the stage is going to attract the attention of the audience . . . away from you. You become "support" to the screen and we all know you don't want that to happen! However, a dark screen with white lettering recedes into the background until you need it. It supports you.
Use the power of light to reinforce key points.
Let's look at "builds." I define builds as short phrases or words that are added to a screen based on a cue. The power of builds is that, if done properly, they visually reinforce key orally delivered phrases, in sync. They can help make a specific idea memorable; set it apart from other screen text.
Now, we know that our eye is attracted by light. So, when building text onto a screen, it makes more sense to "build" white text on a dark background. It will more readily attract the audience's attention.
In television, the eye is attracted by changes on the screen – either the introduction of a lighter color, movement, or both. This is similar to adding white text to a static screen. We perceive movement as the area in question "lights up" with the new text. Adding black text, however, is simply movement and, in fact, may not be that noticeable.
Consider these facts:
Studies have shown that on an LCD panel or CRT (the typical television-type of screen), users are able to read faster when presented with light text on a dark background.
One teacher who teaches large crowds in auditoriums says that unanimously, students prefer chalk on a blackboard over pen on a whiteboard.
Approximately 8% of males and 0.5% of females have a color deficit of some kind. Perhaps that's the reason men have been accused of not complimenting women on their clothing as much as they perhaps should! But seriously, it's one more reason why contrast is so important.
Many with dyslexia find white text on a blue background to be the easiest to read. In fact, Microsoft Word has an option on the preferences panel to turn any page into white text on a blue background.
Don't take your audience for granted!
The only reason I can think of to use black text on white is that it's "easy" to create. However, presenters need to think twice about the effect this phenomenon has on the audience.
It can be more time consuming to develop a light on dark presentation. But the result will be well worth the effort: a higher level of retention, greater audience attention and an increase in perceived professionalism. Logic overwhelmingly points to "light on dark." The very best combinations are white or yellow on a blue, black or dark grey background.
Let's not make it difficult on our "deer audience." Don't force them to stare into the headlights of your projector. Light on dark is the preferred configuration for projected visuals. Otherwise, you stand the chance of completely losing your audience's attention.
And setting yourself up for white death on the podium.
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