The "catch"

"On the Internet, no one knows your a dog" goes the saying - proving your a human on the net is becoming more and more common.

marketing

Accessing applications such as GMail and Twitter normally involves typing a series of letters and numbers called a 'catchpa' to validate access is indeed by a human ... and not a dog or computer system which can open the system for abuse, such as spamming.

technology

The term Catchpa was first introduced back in 2000 to describe a test that can differentiate humans from computers under the following conditions :

Easily solved by humans
Easily generated and evaluated but
Not easily solved by computers

Trouble with catchpa's is they tend to be rather complicated and irrelevant - however they by there very nature command our attention due to our desire to access the services they protect. Attention advertisers are keen to exploit but are finding harder and harder to command.

Your attention

There is also a balance here, how to make the whole experience such that this whole process does not drive away users from your site.

onehandshakeblogspot.com

A neat solution from solve media uses advertisers messages as the catchpa's - moving these brand messages to a point where our attention is high and is likely to have more impact.

The results seem impressive with Solve Media citing 1200% increase in brand recollection over traditional banner ad's, however just how long term would be should everyone adopt this approach is open to debate

Solve Media : click

Understanding CAPTCHA-Solving Services in an economic context : click