Vocabulary acquisition and verbal short-term memory: computational and neural bases

In this paper, we explore the hypothesis that human vocabulary acquisition processes and verbal short-term memory abilities utilize a common cognitive and neural system. We begin by reviewing behavioral evidence for a shared set of processes. Next, we examine what the computational bases of such a shared system might be and how vocabulary acquisition and verbal short-term memory might be related in mechanistic terms. We examine existing computational models of vocabulary acquisition and of verbal short-term memory, concluding that they fail to adequately relate these two domains. We then propose an alternative model which accounts not only for the relationship between word learning and verbal short-term memory, but also for a wide range of phenomena in verbal short-term memory. Furthermore, this new account provides a clear statement of the relationship between the proposed system and mechanisms of language processing more generally. We then consider possible neural substrates for this cognitive system. We begin by reviewing what is known of the neural substrates of speech processing and outline a conceptual framework within which a variety of seemingly contradictory neurophysiological and neuropsychological findings can be accommodated. The linkage of the shared system for vocabulary acquisition and verbal short-term memory to neural areas specifically involved in speech processing lends further support to our functional-level identification of the mechanisms of vocabulary acquisition and verbal short-term memory with those of language processing. The present work thus relates vocabulary acquisition and verbal short-term memory to each other and to speech processing, at a cognitive, computational, and neural level.