Two short-term memory experiments examined the nature of the stimulus suffix effect on auditory linguistic and nonlinguistic stimulus lists. In Experiment 1, where subjects recalled eight-item digit lists, it was found that a silently articulated digit suffix had the same effect on recall for the last list item as a spoken digit suffix. In Experiment 2, subjects recalled lists of sounds made by inanimate objects either by listing the names of the objects or by ordering a set of drawings of the objects. Auditory suffixes, either another object sound or the spoken name of an object, produced a suffix effect under both recall conditions, but a visually presented picture also produced a suffix effect when subjects recalled using pictures. The results were most adequately explained by a levels-of-processing memory coding hypothesis.When subjects are asked to recall items from a list that exceeds the capacity of short-term memory, they typically show a bowed serial position function. That is, recall is better on the first few (the primacy effect) and on the last one or two (the recency effect) list items than on intermediate items. However, under auditory presentation conditions, the addition of one extra item at the end of the list impairs recall for the terminal items, even when subjects are instructed to ignore this suffix and omit it from their recall of the list. This elimination of the recency effect is known as the stimulus suffix effect (Crowder, 1967;Crowder & Morton, 1969). Crowder and Morton (1969;Morton, Crowder, & Prussin, 1971) have suggested a theoretical explanation of the suffix and recency effects based on the precategorical acoustic store (PAS). PAS is a sensory storage system that may last for as long as 2 sec, and that contains auditory information in a relatively unprocessed form. Under normal list presentation conditions, the last one or two elements of the list remain in PAS at the time of recall, giving the subject an added source of information upon which to base his recall of these items. However, a stimulus suffix eliminates most, if not all, of the sensory information about the last list elements from PAS, making recall of them equal to intermediate list items whose traces have also been eliminated from PAS.This research was supported by National Science Foundation Grant BNS76-82337 to the first author and a National Science Foundation Undergraduate Research Participation fellowship to the second author. The authors wish to acknowledge Peter D. Eimas both for providing assistance in the production of the stimuli for Experiment 2 and for giving helpful comments on many phases of this research, and Ann Lee, who collected the data for Experiment 2. Reprint requests should be addressed to Kathryn T. Spoehr, Psychology Department, Brown University, Providence, Rhode Island 02912.The PAS explanation of the suffix effect has been supported by much empirical data. Consonant with this theory, for example, are the findings that nonlinguistic auditory suffixes fail to cause a suffix effect (Crowder, ...