Two experiments were conducted to investigate the presentation-order error that occurs in judgments of sequentially presented temporal intervals. The factors of interest were (1) the source of the errors, sensitivity versus bias, (2) the direction of the errors, and (3) the effect of varying the lSI separating the sequentially presented intervals. Subjects experienced two successively presented time intervals in the range of 1 to 4 sec or 10 to 13 sec on each trial, separated by ISIs of .5-6 sec, and were asked to reproduce either the first or the second interval. Results indicated a negative time-order error for all intervals, such that the intervals were consistently reproduced as longer when presented second rather than first. This time-order error was found to be due to the sensitivity of the processing system, and was interpreted in terms of the recency effect of memory. Presentation order was found to affect sensitivity, whereas lSI was shown to affect reliability of reproductions. lSI had no systematic effect on the size of the time-order error. Implications for time-order error theories and the general importance of the study of presentationorder effects are discussed.Fechner (1860) was the first psychologist to discover and speculate about the nature and cause of the systematic error that generally affects subjects' judgments of sequentially presented stimuli: When discriminating between a pair of successively lifted weights, Fechner observed that the probability of a correct judgment was greater when he first lifted the lighter of the two weights rather than the other way around. Fechner subsequently distinguished between a negative discrimination error (better discrimination when the first stimulus is less than the second) and a positive one (better discrimination when the first stimulus is greater than the second).This presentation-order error, more commonly known as time-order error (TOE), has been the subject of theoretical and empirical attention since the early days of experimental psychology (for comprehensive reviews, see Guilford, 1954;Hellstrom, 1985;Needham, 1934;Woodrow, 1935), and appropriately so: successive stimulus presentation is ubiquitous in cognitive psychological research, and knowledge regarding systematic errors in judgment that occur on the basis of the order in which stimuli are presented is of vital importance for the interpretation of such research. Beyond the psychology lab, successive judgments are probably also more common than simultaneous judgments, and are evidenced, for example, in such varied behaviors as comparing musical per-