Visual signal detection. II. Signal-location identification.

We have measured the effect of signal-location uncertainty on the detectability of simple visual signals in uncorrelated image noise. An M-alternative forced-choice signal-location identification technique was used with values of M ranging from 2 to 1800. We find high statistical efficiency (50% for aperiodic signals), and results from one value of M can be used to predict all others. The results are consistent with the view that humans can act as suboptimal maximum a posteriori probability observers.