DEVELOPMENT OF SHORT TERM MEMORY FOR SPEECH ATTRIBUTES

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DESCRIPTION: This competing continuation proposal examines how short- term memory for attributes of speech and related sounds changes during childhood. It distinguishes between passive, effortless processes (e.g., sensory and phonological memory storage) and active processes that are carried out only if sufficient attention is allocated (e.g., covert articulation and memory search). Whereas past research has focused on developmental changes primarily in a few active processes (e.g., covert verbal rehearsal), the investigator has recently observed substantial decreases in passive forgetting rates across ages, in two different procedures: one in which participants compared the pitches of two slightly different tones separated by a silent interval of variable duration, and another in which participants tried to identify words that were ignored during both their presentation and a subsequent silent interval. The investigator has also obtained a fresh perspective on changes that may occur in active processing. Specifically, in a serial recall task, the durations of silent pauses between words in the spoken responses were found to decrease with development. The results suggested that the pause changes stem from a developmental increase in the efficiency of short-term memory search. Interestingly, pause durations correlated with span but sill were independent of another correlate of span, the speaking rate. The proposed research aims to establish more firmly these newly observed changes in passive and active processing, and to determine their contribution to short-term memory development. The methods involve combinations of the experimental tasks already in use in the investigator's laboratory and variations of those that allow cross-fertilization among them. For example, two-tone comparisons will be examined with the first tone ignored during its presenation, and ignored-speech studies will examine memory for multiword lists. The goal is to determine the relations between tasks in order to identify underlying theoretical mechanisms that enter into more than one of them. Children's passive forgetting rates will be used along with both memory search and speaking rates to predict memory span much more accurately than has been possible until now. The results should lead to an improved theoretical model of normal short-term memory developmental that will be of considerable use in the interpretation and eventual treatment of learning and language acquisition difficulties in children.