Results of ROC analysis in three representative units. A–C, ROC curves constructed from the two distributions of ED: the ED between two single-trial PSTHs, both from the standard duration (10 ms) group and the ED between two PSTHs of the standard and target duration (20, 40, 80, 160, or 320 ms), respectively. D–F, Neurometric functions constructed by plotting the area under the ROC curves shown in A–C against the target duration. Dotted line shows the level of 0.75. Time window used in ROC analysis is 0–400 ms after stimulus onset. G–I, Neurometric functions obtained from the time window of 0–50 ms. J–L, Neurometric functions obtained from the time window of 50–400 ms.