I have some security concerns regarding the image log in method on Windows 8. When I enter the image code the arrows and circles appear for approximately 1 second. It is enough time memorize the pattern for the person behind you. How to disable the appearance of the pattern?
Yes, it might be enough time, depends on people involved. Such questions are subjective however and likely to be closed.
Read the Optimizing picture password security article on the Building Windows 8 blog for more details about the feature. AFAIK it is not possible to disable the visual feedback, which IMO is stupid (sure people might make more mistakes this way, but turning it off should be an option). My personal recommendation is to use a traditional lengthy complex text password (which is anyway the fallback for multiple failed picture password attempts).