Kevin Larson, a researcher at Microsoft's advanced reading technologies group, has found that asking a user to identify the subject of a photo, like a kitten, could help block spam programs.
Services like Microsoft's free e-mail service Hotmail commonly require new users to type in a string of distorted letters as proof that it's a human signing up for the account and not a computer. The trouble is, computers are getting smart enough to recognize the characters and it's a race for Microsoft to continue to alter its HIP (Human Interactive Proofs) system to fool the computers before they catch on.
With 90 billion pieces of e-mail spam sent every day, according to Larson, companies like Yahoo, Google, and Microsoft that offer free online mail services have an incentive to try to block spam. Otherwise they pay for the resources that help send the spam.