In Chapter 9, we traced the coding of a word from its detection by our senses to its processing in sensory and then working memory. In this chapter, we'll complete our tracking of the word's journey by looking at what happens to information about a word once it reaches long-term memory.

Memory systems

At roughly the same time as Baddeley and his colleagues were suggesting that short-term memories are formed in separate subsystems, evidence was mounting that the same is true of long-term memories. The nature of the systems in long-term memory, however, was a matter of considerable theoretical dispute. You can obtain a sense of how widely the theories differed if we simply list some of the terms that theorists have used to describe these systems: conscious and unconscious memory (Kelley and Lindsay, 1996), implicit and explicit memory (Graf and Schacter, 1985), procedural and declarative memory (Squire, 1987), episodic and semantic memory (Tulving, 1972, 2001), and perceptual and conceptual processing (Roediger and McDermott, 1993; Schacter and Tulving, 1994). Despite this dazzling – or daunting – proliferation of explanations, the differences between the theories have narrowed over time, to the point where the two most influential accounts – those of Schacter and Tulving (1994) and Squire (2004, 2009) – are almost identical, differing more in terminology than in basic assumptions.