Best text/copy to label a CAPTCHA with?

Question

I don't want to hear why CAPTCHA's suck for user experience, I already know the pros and cons.

I am using CAPTCHA on a website that has an older audience that may not be familiar with what CAPTCHA's are and what their purpose is, unlike in this discussion. With that in mind, what is the best text to label the CAPTCHA with? The goal is to inform users as quickly as possible what to do without confusing them.

Here are some common examples:

"Are you human?"
"Please enter the following text in the box below:"
"Security Check:"

I'm not sure if these examples have sufficient explanation, but if you put too much explanation it may be overwhelming... see this example:

Thoughts?

Answer 1

What is the site about? That might make a difference. I think in general, something like "For your security, please enter the text you see in the box below" could work, although really, it's not for their security at all. Maybe just say "Please enter the words you see into the box below." Sometimes giving too much explanation will confuse people more than just asking them nicely. I think that many of that older generation will recognize a captcha, and if they don't, they will feel inept enough to obey polite instructions like this on a website. :)

Answer 2

I think what ever you pick for the CAPTCHA prompt, what works best are those prompts that explicitly ask the user to do a task ("Please enter the following text in the box below:") instead of those that explain to the user what CAPTCHA is for ("Are you human?" or "Security Check:").

On our site, which also has an older audience, we use:

"For your security, please type the words that appear below into the entry box."