Captcha's are lame

A captcha is an acronym for “completely automated public Turing test to tell computers and humans apart – in other words a type of challenge-response test used to determine whether or not a computer user is human (or another computer).

From the Wikipedia entry on Captcha’s:

A common type of captcha requires that the user type the letters of a distorted and/or obscured sequence of letters or digits that appears on the screen. Because the test is administered by a computer, in contrast to the standard Turing test that is administered by a human, a captcha is sometimes described as a reverse Turing test

Recently, I have seen several bloggers install captcha’s as a way to try to stop comment spam on their site – guys, captcha’s are lame.

Captcha's are lame

Why are captcha’s lame? Captcha’s are lame because:

  1. they force the burden of work back on your commenter and pushing extra work on your readership displays a lack of respect
  2. they show you are too lazy to properly secure your blog against comment spam (using blacklists, .htaccess, number of links, etc.) and most importantly,
  3. they discriminate against partially-sighted readers

There are many good anti-comment spam tools and procedures available, don’t use captchas.

13 thoughts on “Captcha's are lame”

  1. Tom, I couldn’t agree more. Some peoples’ implementation of Captcha is just asinine. I posted something a while back titled “CAPTCHA Honkers” because I was pissed with a poor implementation at Doug Kaye’s ITConversation that caused me to lose my entire post. Pathetic.


    btw, loved the show with Salim Ismail this morning. I’ll blog on it when I can. The implications of standardized structured documents with an alerting system are enormous.


  2. I wouldn have to disagree. Some implementations of captcha are terrible. Captcha, however, is a very good method of blocking comment spam – if done properly.

    To take your points:
    1 – If the person wants to say anything then they can. Properly implemented captcha is hardly that much of a hindrance and using the arguments that I would use against CR is hardly suitable.

    2 – That’s ridiculous. If a blogger allows you to comment on their posts it is their choice how they wish to stop the comment spam. Saying that they are being lazy is, frankly, lazy on your part.

    3 – That depends on the implementation

  3. I’m glad I checked back here, because Michele is right. Captcha is a very effective spam preventer. I’ve been using it for at least a year and no one has complained with my simple, easy to read 3-digit numeric request. I didn’t make it clear in my earlier comment, but I completely support captcha when implemented with the readers’ best interests in mind–when its simple, easy, readable, preserves posts, and works as designed.
    1) 3-digits (all you need) is not a burden, 2) agree with Michele. captcha works, despite its simple design, 3) use big numbers (implementation.)

  4. 3 – That depends on the implementation

    No it doesn’t Michele – the American Foundation for the blind has written many times about how difficult Captchas make browsing for blind or partially sighted people.

    And even if you think they don’t know what they are talking about or are just being “ridiculous” – how about the W3C – the W3C in a report on Captcha”s said:

    A common method of limiting access to services made available over the Web is visual verification of a bitmapped image. This presents a major problem to users who are blind, have low vision, or have a learning disability such as dyslexia.

  5. Tom,

    You’ve visited my blog so you may remember I employ a simple, effective captcha. It works.

    If the argument is whether or not captcha discriminates against partially-sighted readers because they are bitmapped images, then OF COURSE, we would all be in agreement. But you never mentioned that in your original post. _I_ never knew there were technical implications of bitmapped displays and partial-sighted readers. Make that your argument with the WC3 findings on the topic if you want to argue about something. I’m glad to learn about that.

    And Michele used the term ‘ridiculous’ regarding your second point on captcha being an indication of the blogger or blog admin being lazy, NOT the partial-sighted reader issue. She was certainly not slamming the WC3 findings. You never mentioned those points in your post!


  6. @ Dave, my point 3 in my original post did mention that captcha’s discriminate against partially sighted readers – I didn’t go into any detail on that because I believed (incorrectly obviously) that it was self-evident.

    @ Michele – not intentionally, no. I was going to title it “captchas are evil” but I thought lame is closer to reality than evil.

  7. “lame” in the context you are using it is not an English word – unless you are trying to be metaphorical ergo I would consider it a pure Americanism albeit unintentional on your behalf

  8. Michele, sorry! I guess that’s actually you in the turtle neck on your blog. That’s what I get for being only half-Irish.

    Tom, thanks for the follow-up on point 3, which was exactly my point on your assumption that the masses of lame thinkers like myself know anything about the ramifications of text vrs. bitmapped image generation with the visually-impaired.

    Whew, I’m glad we settled that! I can now blog on your excellent show with Ismail now (part I. Haven’t listened to part II yet.) I was thinking I was going to have to bad-mouth it there for a while. šŸ™‚

    Hey, Michele. What’s wrong with fawning to an American Audience? Lame is a darn-fine word! And just think of all of the intelligent debates you can engage in bringing in American comments. Maybe not about captcha, but a lot of other stuff, I’ll bet!

  9. Another reason Captchas are lame: they are doomed to fail from the get-go. At best, their spread will result in an arms race between Captcha developers and AI programmers (both malicious and benign-but-curious) who will write increasingly clever image analysis routines.

  10. Interesting post but disagree on a number of counts.

    1. they force the burden of work back on your commenter and pushing extra work on your readership displays a lack of respect.

    Entering a few letters could hardly be classified as “extra work”. I most certainly do not disrespect any reader of my blog. To suggest I do is disrepectful in itself.

    2. they show you are too lazy to properly secure your blog against comment spam (using blacklists, .htaccess, number of links, etc.) and most importantly,

    .htaccess? What’s that? Great for the technically adept. But what about everybody else?

    3. they discriminate against partially-sighted readers
    True. Like an awful lot of software I suspect.

    The burden to captcha or not should rest with the blog software providers, not the bloggers.
    Apart from that, good blog. Keep it up.

  11. Captchas seems to be pretty effective against casual spammers. It doesn’t seem that akismet outlined clearly how they detect and stop spams.

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