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To Captcha or Not to Captcha

Don’t you hate it when open your email and see lots of web lead announcements — and then you click through and discover that they’re from udyufdyuyyyyyyy@163.com offering you cheap Ugg boots? Your happy anticipation is turned to frustration and anger. If you get lots of web leads, they take up your valuable time (or the time you pay other valuable people for). If you don’t get lots of web leads, they add insult to injury by disappointing you.

We often hear frustration from clients because they see more spam as we work for them. This is the price of visibility. A website that begins to attract attention will get attention from spambots as well as from customers. One solution is to add a Captcha. Captchas ask visitors to prove their humanity by typing in the letters or numbers that they see, doing a math problem, or otherwise completing a task that is easy for a human but hard for a machine. Here’s a simple example:


Is it worth installing Captchas?

The first question is, will they stop bots? The answer is “No.” First, there are plenty of applications that will solve most Captchas automatically. If you have a clever Captcha that defeats machines, the spammers have a back up plan: use humans, but use them only to solve the Captchas.

I once tested software that placed links automatically. The software zipped along filling out forms and sent me all the Captchas it couldn’t handle. I, being a human, could take care of all the Captchas very quickly, while the software did the time consuming part. This method will completely solve all Captcha issues, and it’s amazing how many people will do this sort of work for almost nothing.

So your Captcha might slow down the flow of spam by eliminating the most primitive bots, but it won’t stop it.

The more important question

The more important question is, will Captchas stop human visitors from filling out your forms? A casual experiment reported at Moz concluded that Captchas cut spam submissions, though they didn’t eliminate them, but that they also cut actual conversions by more than 3%. The number could actually have been larger — the experiment considered only submissions that attempted the Captcha and failed, not those that went to the contact page, saw the Captcha, and left.

You also need to think about your company’s audience. A study in 2009 found that people with limited vision took an average of 65 seconds to solve audio Captchas, and even then they only got them right 45% of the time. These were people with such severely limited vision that they chose the audio Captcha. How many of your visitors are not in that category but still find Captchas challenging?

One way to find out is to think about your demographics. Age-related visual limitations begin at 41. By 55, nearly all Americans have some vision changes. By 65, your visitors probably can’t do Captchas as well as a spambot can. Are you offering retirement planning services? Cruises? Luxury cars? Luxury travel? High end toys (people buy those for their grandchildren)? Health care products? High end beauty products? Don’t use a Captcha. 75% of Baby Boomers shop online and they spend $700 million a year.

What’s more, according to Forbes, they are the top spenders in 119 out of 123 CPG categories, including electronics. Unless you’re sure your demographic is younger, it’s not worth the risk of losing the humans.

Younger visitors and Captchas

We’re using firm data about older visitors to conclude that they may have trouble with captchas and therefore be unable to fill out your forms. We haven’t seen strong research about younger visitors’ feelings about Captchas, but asking around made it pretty clear that most of the people we know will at least sometimes choose not to use a Captcha. Even if it means that they don’t get to fill out a form.

Our conclusion: if you get so much spam that you just can’t handle it, install captchas. If your conversions fall so much that you’re unhappy, remove them.






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