Bounds on the area under the receiver operating characteristic curve for the ideal observer

A new upper bound is derived on the area under the receiver operating characteristic curve for the ideal observer in a signal-detection task. This upper bound is determined by the values of the likelihood-generating function and its second derivative at the origin. This bound is compared with other bounds on ideal-observer performance that have been derived recently, and it is also shown how this bound leads to some asymptotic results for approximations to ideal-observer performance.