US Patent 9069942 Method and device for confirming computer end-user identity

The identity of an end-user operating a computer is confirmed by analyzing user reactions to aberrations in output. More specifically, an aberration is caused in output that the computer provides to an output device, and the end-user's response to the aberration is received. An end-user characteristic is extracted from the response and compared to stored characteristic responses to find a match. A match is indicative of the identity of the computer user. It can also be checked whether, after causing an aberration in output the end-user responded differently to the output than if the output did not have the aberration. The lack of a different response can be interpreted as indicative that the end-user is a bot.