Using Radio Buttons to Combat Form Spam
10/10/2007There has been a lot of talk lately (and rightly so) about the disadvantages of using captcha to stop comment spam.
I’m not a big fan. They’re often hard to read even for someone with reasonably normal vision.
“Is that a zero or the letter O?”
“Upper case C or lower case c?”
Others have suggested some sort of simple logic question, like asking “What’s 1+1″ and having the user enter a ‘2′ in a text box.
That might be better, but it also requires some thought.
So I noticed that on Slideshare they prefix a captcha device with the question, “Are you human?”
And it got me thinking, can bots deal with radio buttons? Can we ask a question like this?
<form> Are you human?<br /> <input type="radio" name="Human" value="No" checked="checked" /> No, I'm a spam robot<br /> <input type="radio" name="Human" value="Yes" /> Yes, I am human <br /> </form> </body> </html>
Download this code: human_form.htm
I must admit I haven’t done any research, but I’m thinking:
- If a bot doesn’t understand radio buttons it will skip the question and fail
- If it does understand radio buttons, it will probably choose the first option and fail
- It’s an extremely simple question for a human to answer and should be completely accessible.
Point 2 is probably the most contentious. I’m making a big assumption there.
Has anyone else tried this? Can anyone spot any obvious disadvantages?