The distinction between categorical and continuous modes of perception has played a central role in discussions of speech perception. Recent findings of Fujisaki and Kawashima [J. Acoust. Soc. Amer.47, 57 (1970)] suggest that these two modes are not necessarily dichotomous but may be related to the degree to which some brief auditory short‐term memory store is employed during discrimination. The present experiment examined discrimination performance within and between phoneme boundaries using a delayed comparison AX same‐different task. The delay interval between presentations of the standard and comparison sounds varied over a range from 0–2.0 sec for each of four types of synthetic speech stimuli. For steady‐state vowels accuracy of discrimination both within and between boundaries was related to changes in the delay interval. Discrimination of stop consonants remained relatively stable both within and between boundaries. The results suggest that vowels (even as short as 50 msec in duration) are stored differently than stop consonants in auditory short‐term memory. [Research supported in part by grant to Haskins Laboratories from NICHD.]