The familiar term CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) refers to a program that generates and grades tests that humans can pass but computers cannot. A common example of a CAPTCHA is the distorted text that you sometimes have to read when doing a secured online action, such as purchasing concert tickets or posting a comment on a blog. Even though everyone hates CAPTCHAs, they have many objectives, including:

  • Preventing comment spam in blogs
  • Protecting website registration
  • Securing online polls
  • Preventing dictionary attacks
  • Search engine bots
  • Worms and spam

On or Off: How CAPTCHA Impacts Conversion Rates

For webmasters, the choice to use CAPTCHA isn’t always straightforward. Turning the CAPTCHA on may seem to be the smartest move at first, as dealing with spam can be a huge headache. And, since we have yet to perfect a spam-fighting solution on web forms, CAPTCHA is the only thing available to somewhat control spam. But, how exactly does CAPTCHA affect the conversion rates of web forms?

A study done by Casey Henry looked at this very relationship. Henry’s study reviewed 50 websites over the course of six months, switching the CAPTCHA to “on” for three months and then “off” for the next three months. What he found was that when the CAPTCHA was turned on, there was an 88 percent reduction in spam, but 159 failed conversions. Since conversions are largely responsible for making money, the study found that leaving the CAPTCHA off was better. In this particular case, 3.2 percent of failed conversions could have been sales.

This study is just one example that looks at CAPTCHA and how it affects conversion rates, so the choice is still up to you. Is it worth it to remove the few spam posts and ensure that you’re not missing out on possible income? Or would you rather take the work out of controlling web spam and focus on quality leads? After all, in Henry’s study, it was possible that the percentage of failed conversions were spam.

Even though there are mixed comments about CAPTCHA, the majority of webmasters agree that turning off the CAPTCHA is better for conversion rates and the user experience as a whole.