The relationship of signal identification to signal detection was examined in a series of experiments. The signals were idealized lines and patterns of lines in a spectrographic display. On each trial, progressively more of the complete spectrogram was exposed in successive observation intervals, and after each interval the observer made both detection and identification responses that were based on the accumulating evidence. One model we employed conceives of detection and identification as proceeding together over time as parts of a unified process. A second model used shows how thejoint detection-and-identification ROC—a relative operating characteristic that relates the joint probability of correct detectionand correct identification to the probability of a false detection—may be predicted from the simple detection ROC. Both models were supported by the data.