<P>PROBLEM TO BE SOLVED: To provide an improved CAPTCHA easily solved by man's visual sense but difficult for a machine. <P>SOLUTION: Deciphering displayed characters 'ABCD' is a task. It is loop animation, and the characters 'ABCD' moves upward. The foreground moves from right to left, and a foreground layer always shields a part of the characters 'ABCD.' A user sees a part of a solution at each point of time and integrates each part to read the whole. A human sense to motion is used to prepare various CAPTCHAs difficult for the machine but easily solved by person, and the CAPTCHA beautiful to look at can be prepared. <P>COPYRIGHT: (C)2008,JPO&INPIT 
CAPTCHA (COMPLETELY AUTOMATED PUBLIC TURING TEST TO TELL COMPUTERS AND HUMANS APART) OF MOTION AND INTERACTION BASE