Why can’t computers complete CAPTCHAs?

Common CAPTCHAs have been around since 1997, but computers are a long way behind the human brain at cracking them.

29th February 2016
Why can’t computers complete CAPTCHAs? (iStock)

Asked by: James Malpas, Histon

On a website’s login page, CAPTCHAs are those obscure-looking characters we use to verify that we are human users and not bots. The characters are often distorted with the letters or numbers running into each other. Optical character recognition software struggles to pick out the individual forms, especially when their shape and size vary from one CAPTCHA to the next. 

 

Read more: 

 


SFQASubscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.