Psychological Review 1998, Vol. 105. No. 1, 158-173 Copyright 1998 by the American Psychological Association, Inc. 0033-295X/98/J3.00 The Phonological Loop as a Language Learning Device Alan Baddeley and Susan Gathercole University of Bristol Cpstanza Papagno Universita Degli Studi di Milano A relatively simple model of the phonological loop (A. D. Baddeley, 1986), a component of working memory, has proved capable of accommodating a great deal of experimental evidence from normal adult participants, children, and neuropsychological patients. Until recently, however, the role of this subsystem in everyday cognitive activities was unclear. In this article the authors review studies of word learning by normal adults and children, neuropsychological patients, and special developmental populations, which provide evidence that the phonological loop plays a crucial role in learning the novel phonological forms of new words. The authors propose that the primary purpose for which the phonological loop evolved is to store unfamiliar sound patterns while more permanent memory records are being constructed. Its use in retaining sequences of familiar words is, it is argued, secondary. Baddeley and Hitch (1974) considered the possibility that short-term memory (STM) may serve as a general working memory designed to support complex cognitive activities. This suggestion led to the development of a specific multicomponent model of working memory and has subsequently contributed to an enduring interest in the specific cognitive functions that are fulfilled by the separate subcomponents of working memory. The aspect of working memory for which the fullest theoretical account is now available is the phonological loop (Baddeley, 1986). The loop is specialized for the retention of verbal infor- mation over short periods of time; it comprises both a phonologi- cal store, which holds information in phonological form, and a rehearsal process, which serves to maintain decaying representa- tions in the phonological store. This relatively simple model has proved capable of accommodating a great deal of experimental evidence from normal adult participants, children, and neuro- psychoiogical patients (see Baddeley, 1997, and Gathercole & Baddeley, 1993, for reviews). Although the evidence for the existence of such a short-term system is strong, it is not obvious why the phonological loop should be a feature of human cognition at all. People have a remarkable capacity to repeat what they hear, a capacity that Alan Baddeley and Susan Gathercole, Department of Psychology, Centre for Study of Memory and Learning, University of Bristol, Bristol, England; Costanza Papagno, Clinica Neurologica III, Universita Degli Studi di Milano, Milano, Italy. Much of the work reported in this article was supported by the Medi- cal Research Council (MRC) of Great Britain and the Economic and Social Research Council. The support of MRC Grant G9423916 during the writing of the final draft is gratefully acknowledged. Finally, we are very grateful to Dorothy Bishop of the MRC Applied Psychology Unit Cambridge for stimulating discussion and making many constructive suggestions. Correspondence concerning this article should be addressed to Alan Baddeley, Department of Psychology, Centre for Study of Memory and Learning, University of Bristol, 8 Woodland Road, Bristol BS8 ITN, England. Electronic mail may be sent via Internet to alan.baddeley@ bristol.ac.uk. has extensively been investigated by using lists of digits or unrelated words. When looking for a function that this capacity serves, Baddeley and Hitch (1974) concentrated on asking why it should be useful for people to remember sequences of words, and this led them to study comprehension and verbal reasoning. However, the evidence of a major role for the phonological loop was far from compelling (see Baddeley, 1986, for review). Indeed, much of the neuropsychological evidence that has led to the development of the current model of the phonological loop (e.g., Vallar & Baddeley, 1984) itself raises questions about its function. Many individuals with specific deficits in short- term phonological memory appear to have few problems in coping with everyday cognition: Despite dramatic reductions in the capacity of the phonological loop, such individuals typically have normal abilities to produce spontaneous speech (Shal- lice & Butterworth, 1977) and encounter few significant diffi- culties in language comprehension (Vallar & Shallice, 1990). Does this mean that the loop is of little practical significance and that at least this aspect of STM does not serve as a working memory? Some authors have argued that this is indeed the case (Butterworth, Campbell, & Howard, 1986). The purpose of the present article is to propose that the phono- logical loop does indeed have a very important function to fulfill, but that it is one that is not readily uncovered by experimental studies of adult participants. We suggest that the function of the phonological loop is not to remember familiar words but to help learn new words. According to this view, the ability to repeat a string of digits is simply a beneficiary of a more fundamental human capacity to generate a longer lasting representation of a brief and novel speech event—a new word. For anexperimental psychologist working exclusively with adults, this might at first seem a singularly arcane and useless skill for humans to possess. For a developmentalist, though, the point of such a skill is all too evident because the task of forming long-term representations of novel phonological material is a key component of language development. At a conservative estimate, the average 5-year-old child will have learned more than 2,000 words (Smith, 1926) and will learn up to 3,000 more per year in the coming school years (Nagy & Herman, 1987). Indeed, successful vocabulary