Thinking About CAPTCHA’s… Briefly

July 21, 2009 at 7:30 PM

in Operations,Services,Social Software

The Akismet folks mentioned yesterday via a post on their blog about CAPTCHA conversion rates, as discussed at the SEOmoz blog. While the very informal study done by the author of the SEOmoz blog post had a very small sampling (some statisticians may even say, “Whoa! Statistically insignificant!”), and the sampling methods were arguably questionable, it nevertheless shows an attempt to quantify whether CAPTCHA’s represent a matter of greater resistance toward attracting comments, as opposed to sites which do not use them (such as Javamancy).

Good? Bad? Indifferent?

Most visitors tend to be indifferent toward CAPTCHA’s, until they encounter them. Then, it seems that, depending on the urgency of the topic and the fervor that they experience at the moment, the visitors may decide typing a few oddly-shaped characters into a text field– in addition to any registration info they may also have to type into other fields– is worth the effort. The problem is that, measuring the impact of the content itself against the conversion rate of the CAPTCHA’s is a bit more involved and unfortunately was not considered in the SEOmoz test. As for the 50 sites, which would address the differentiation of content-value and popularity-traffic test elements, not knowing which ones are higher point value than the others also throws into question whether the volume of submissions makes sense.

Still good? Or bad? Or indifferent?

Yep, didn’t think it mattered, either. :-)

If you have been relying upon CAPTCHA’s and/or their variants, you will most likely continue. If you have been “going commando” all this time, you may feel obligated to investigate further the possibility of using CAPTCHA’s or some other comment/post protection scheme. If you have incorporated CAPTCHA’s as part of a more comprehensive protection pattern, you may toy with the idea of shutting them off to see how your sites fare.

Remember, gentle readers: YMMV. ;-)


Fortunately, the controversy around CAPTCHA’s is not as hotly debated/argued/stomped as, say, GPL:

Other title candidates:

  • Need Resistance to Your Site? Try CAPTCHA’s!
  • Ooh Boy! Shake It Up with CAPTCHA’s
  • Who Cares About CAPTCHA’s?
  • CAPTCHA’s Today, CAPTCHA’s Yesterday, CAPTCHA’s… Maybe Not Tomorrow

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