It's happened to all of us.
You go to your inbox.
You open an email, and you see it.
It's something that has been sent -- not just to the recipient -- but "reply all"
... to everyone ...
... including lots of people it wasn't supposed to go to.
Sometimes we've been on the receiving end, and it's cringeworthy; but of course it's
even more mortifying if you were actually the sender, and you've sent something out
to your entire workplace of 200,000 people or your campus or your community.
That is not user error.
In fact, it's the design error.
The design failed to prevent the user from accidentally clicking that reply-all button.
Now, this concept of error prevention is one of Jakob Nielsen's heuristics.
It's one of these most important concepts to have good usability in a design.
Let me show you something I found the other day that was actually wonderful.
This is my electric toothbrush, which does a great job at cleaning my teeth, but it also
has a nice feature designed to prevent me from forgetting to charge it.
When I finish brushing my teeth and its battery is running low, it vibrates three times.
It makes a little sound.
It goes "Brrrm brrrm brrm!"
Something like that.
And that tells me that I need to plug it in.
Now what's the worst that could happen if I forget to charge this toothbrush?
I can still brush my teeth just fine.
But there are plenty of designs where the stakes are actually really high.
Those of you who might be designing things for use in medical scenarios, in transportation,
in security, or finance -- where, if someone accidentally starts to reach for the wrong button,
it could have really serious and damaging consequences.
So, error prevention is critical.
If you're looking at your designs, I want you to start with the issues that might cause severe damage.
Then, go down and look at things that you can do to prevent simple annoyances and frustrations,
and prevent people from having to redo their work.
Sometimes these are simple fixes like changing size, the color, or placement, location of a button;
sometimes changing the texture of a button if you're in the physical world.
Other times, it's offering a confirmation dialog that says, "Are you sure you want to
transfer all of your money to this other account?"
It's worth the interruption because you want to prevent an accidental transfer.
And last, having an undo button is a great way to at least prevent errors from becoming permanent.
If someone goes down that path of making a mistake, they can still catch it and hopefully undo.
So, when you're looking through your designs take the time to find out ways that you can
stop errors before they happen.
And in the meantime, stay clear of that reply-all button.