How can the CAPTCHA process be more user friendly or better implemented?

Question

I have used CAPTCHA on my various web sites in the standard manner where I generated some obfuscated string of characters (odd pair of words, random number, etc.) in an image for the user to manually reproduce in a text box. I am also aware of recaptcha.net which extends the basic functionality of screening bots from humans and as well as helping to digitize books. I just came across another way of performing CAPTCHA with the AJAX Fancy CAPTCHA jQuery plugin which rather than asking the user to reproduce a string instead asks the user to drag an image that is readily recognizable (scissors, pencil, book, etc.) into an area that is equally recognizable. When I saw this I had to say to myself "WOW...that's cool!"

Question: Does anyone out there have any other examples of a neat and different way of performing CAPTCHA without having to generate a random string of characters into an image for the user to try and read (or regenerate until they can) so that they can manually type it into a box?

Answer 1

I know I am not particularly helpful in this answer, feel free to downvote me if it's the case, but I want to present my technical opinion (albeit of a non-expert) on captchas.

As someone said, the captcha is an antipattern of the web. Its purpose is to let you demonstrate that you are human, by doing something that only a human (purposely) can do. Fact is that, despite the captchas, the only achieved result has been to improve pattern recognition for software, producing better bots. In this sense, it can be said that the final, real purpose of captchas was not to select humans from bots, but select better bots (or cheap workers) from lousy ones.

What you are asking is actually a matter of current research. I've seen stuff like selecting cats from dogs, solving simple math problems, recognizing apples from oranges, counting the number of people in a photo, but in the end I doubt you will get something more proficient or user friendly than what's currently available. In the end, the pure fact of having to solve a captcha is user-unfriendly.

Answer 2

You can have your users tell dogs and cats apart. Microsoft's Asirra.

Answer 3

I'd like to see ReCAPTCHA implemented for images that a computer can't tell whether or not they're pornography. Web filter companies could pay free porn sites to use this system to better fill out their blacklists. The free porn sites could then make more porn, and the web filters would have more porn to block.

Answer 4

A CAPTCHA should be a last resort, having tried other alternatives. For example you can use a honeypot technique, that uses a form field that’s invisible to a user but visible to a bot – if it gets filled in, you know it’s not from a human.

In some cases you can experiment with softer CAPTCHAs like riddles or simple math problems. The best tactic - from a User Experience perspective - is to start as soft as possible, and only ramp up if bots become a real problem.

Answer 5

Here's a human-friendly captcha that asks users to identify pictures of various things: http://www.confidenttechnologies.com/products/confident_CAPTCHA.php

It's tough on bots becuase it presents a grid of images that change with each session and it has many different categories of images. It's easier on people, though, because it's easy for people to recognize pictures of common things like dogs, flowers and cars.

As far as the issue of preventing teams of people used in other countries to break captchas for money, a partial solution would be to incorporate some intelligence and risk analysis into the captcha so the captcha can become more difficult or require more steps if the user is from a suspicious IP address or is attempting to solve hundreds of your captchas daily. If the captcha is more difficult for these teams of people, then they can solve less per hour and it becomes a deterrant because it is not as profitable for them. They would have to have a strong desire to attack that specific site, rather than just go to some other site that doesn't have captcha or has a weaker captcha.