1. A computer-implemented method for determining a controlling entity of a first avatar in a virtual world, the method comprising: receiving, via the computer, a request for access to a resource via a first avatar; providing, by the computer, a challenge to the first avatar in response to receiving the request; receiving, via the computer, a challenge response via the first avatar in response to the challenge; determining, by the computer, an identity confidence level based on the challenge response, wherein the identity confidence level is a numerical value determined based at least in part on a cross-correlation between an image and a matched filter; calculating a difference between the cross-correlation and an autocorrelation; making, by the computer, an identity determination for a controlling entity of the first avatar based on the identity confidence level; and providing or denying, by the computer, access to the resource based on the identity determination.