Here is an excerpt from a terrific article written by Susan Weinschenk for Business Insider. To read the complete article and check out a wealth of valuable resources, please click here.

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I’ve decided to start a series called 100 Things You Should Know about People. As in: 100 things you should know if you are going to design an effective and persuasive website, web application or software application.

Or maybe just 100 things that everyone should know about humans!

The order that I’ll present these 100 things is going to be pretty random. So the fact that this first one is first doesn’t mean that’s it’s the most important, just that it came to mind first.

[Here are the first two of Weinschenk’s 47.]

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#1 — You Have “Inattention Blindness”

First let’s start with a little test for you to take. Please watch this video:

This is an example of what is called “inattention blindness” or “change blindness”. The idea is that people often miss large changes in their visual field. This has been shown in many experiments.

So what does this mean if you are designing a website or something on a computer screen? It means that you can’t assume that just because something is on the screen means that people see it. This is especially true when you refresh a screen and make one change on it. People may not realize they are even looking at a different screen. Remember, just because something happens in the visual field doesn’t mean that people are consciously aware of it.

Here is a change blindness experiment that was recently conducted.

[Please click here and scroll down.]

#2 — You READ FASTER With a longer Line Length But PREFER Shorter

Have you ever had to decide how wide a column of text you should use on a screen? Should you use a wide column with 100 characters per line? or a short column with 50 characters per line?

It turns out that the answer depends on whether you want people to read faster or whether you want them to like the page!

Research (see reference below) demonstrates that 100 characters per line is the optimal length for on-screen reading speed; but it’s not what people prefer. People read faster with longer line lengths (100 characters per line), but they prefer a short or medium line length (45 to 72 characters per line). In the example above from the New York Times Reader, the line length averages 39 characters per line.

The research also shows that people can read one single wide column faster than multiple columns, but they prefer multiple columns (like the New York Times Reader above).

So if you ask people which they prefer they will say multiple columns with short line lengths. Interestingly, if you ask them which they read faster, they will insist it is also the multiple columns with short line lengths, even though the data shows otherwise.

It’s a quandary: Do you give people what they prefer or go against their own preference and intuition, knowing that they will read faster if you use a longer line length and one column?

What would you do?

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Dr. Susan Weinschenk is the author of Neuro Web Design: What makes them click? and soon-to-be published 100 Things Every Designer Needs To Know About People. All 47 articles that have been republished from her website at which you will find a wealth of valuable resources.