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A commonly expressed view is that short-term memory (STM) is nothing more than activated long-term memory. If true, this would overturn a central tenet of cognitive psychology—the idea that there are functionally and neurobiologically distinct short- and long-term stores. Here I present an updated case for a separation between short- and long-term stores, focusing on the computational demands placed on any STM system. STM must support memory for previously unencountered information, the storage of multiple tokens of the same type, and variable binding. None of these can be achieved simply by activating long-term memory. For example, even a simple sequence of digits such as “1, 3, 1” where there are 2 tokens of the digit “1” cannot be stored in the correct order simply by activating the representations of the digits “1” and “3” in LTM. I also review recent neuroimaging data that has been presented as evidence that STM is activated LTM and show that these data are exactly what one would expect to see based on a conventional 2-store view.

For more than a century most psychologists have accepted that there are distinct memory systems responsible for long and short-term storage. Originally based entirely on introspection (e.g., James, 1890), the idea that there are separate long- and short-term memory (LTM and STM, respectively) systems subsequently became a core assumption of modern cognitive psychology. From the 1960s most cognitive models of memory have assumed that there are separate stores (Atkinson & Shiffrin, 1968; Baddeley, 1986; Baddeley & Hitch, 1974; Brown, Preece, & Hulme, 2000; Burgess & Hitch, 1992, 2006; Lewandowsky & Farrell, 2000; Page & Norris, 1998a, 1998b, 2009; Waugh & Norman, 1965). This remains the framework guiding almost all cognitive work on verbal...