Fig. 2

Equal-variance Gaussian signal detection model for a showup or a lineup. For a showup, the model operates in the same way that it does for a standard old/new recognition memory test. For a lineup, the simplest decision rule holds that a positive identification (ID) is made if the memory-strength of the strongest item in the array (considered in isolation) exceeds criterion, c₁. In that case, the confidence rating associated with the ID depends on the highest confidence criterion that is exceeded (e.g., the confidence rating is 5 if the strength of the most familiar face exceeds c₅)