It’s all about the eye line and distance. The bigger your prompter screen is, the farther back you can throw from to reduce the eye travel.
While I like Todd, I have a point of disagreement with him regarding fonts. Studies and my field experience confirm that all-caps is an inferior way to present text for prompting. All-Caps is actually a holdover from the bad old days of prompting, where you actually typed onto rolls of paper using a custom typing ball and electric typewriter. Your “cut and paste” word processing in those days actually used scissors, white-out, and tape! The rolls unspooled on a conveyor belt past a black and white camera that generated a luminance key output to the mirror assembly, so the fonts had to be fat and readable to that camera first and an eyeball second. When early, fully-electronic prompting systems came into operation, their font selection was also limited because RAM was expensive, so you still only had one all-caps font after you did away with the conveyor belt-camera-paper roll contraptions. So many folks grew up working with all-caps by default. Not because it was a better way.
We read by decoding word shapes, seeing the word as a whole, not as individual letters. The fastest decoding of that shape relies on it being upper and lower-case letters, with ascenders and descenders, creating that word shape. Ever watch Sesame Street or Electric Company? They teach reading using mixed case for the same reason. Indeed, typically you run several lines of type on a prompter screen at any given moment, because the brain is actually speed-reading ahead of your consciousness, pre-decoding the next row of words using your peripheral vision, before you are actually at that point. It’s one of the keys to “speed reading”. It is this subconscious background processing you lose if you blow up a font too huge and reduce the number of words per line. When you lose that, you also lose speed and comprehension.
ALL CAPS destroys the learned shapes of words and sends you back to decoding each word a letter at a time. Worse than that: you are first decoding a capital letter, then deciding if it needs to be capital for a specific meaning, like the first letter of a person’s name, (Washington, or is it washing a ton of stuff) then if it is not a cap in normal usage, the brain continues to process it into the lower case letter and THEN is lining up the translated lower case letters to make the overall word shape in your brain instead of on the page. This is like when someone writes a page full of bad HTML instead of a single simple tag to get a job done: it’s just bad coding!:-)
Your brain can decode all this, of course, but it is going to have to work a little harder and take a fraction of a second longer to do it, and there is some increased chance of an error without the word shape to match against. Try reading an entire page of something in all caps some time and then again in mixed case and see which one “feels” easier to read.
Old-time newsreaders had no choice in the matter; they only had all-caps and simply re-trained themselves over time to deal with this, then stuck with it. Stingy, slow-to-update newsrooms then perpetuated this “standard” well beyond it’s heyday. (It’s like the old anecdote about why mom cuts the ends off her beef roasts when she cooks them.)
There has been some experimentation with a completely different prompting scheme, it relies even more on word shape, because instead of lines of words it sequentially projects a SINGLE word at a time, in the same space, with no travel up, down, or side-to-side. Something like the device called a tachistoscope. It takes a little getting used to, but enables a fairly fast reading speed, while being readable from a distance though using the very smallest of screens. In a sense, this is the farthest extension of what Todd was talking about and his method of presentation. One word that fills the screen, replaced with another single word that fills the screen, all centered and never in motion, only scaled based on number of letters it takes to cover the screen left to right. It has been used in some on air spots from time to time as a catchy and edgy way to put up text without loading up the screen. You might try it as an experiment some time, just for kicks.
Unless you’re epileptic; then take it slowly, please.