Explaining the Course of Skill Acquisition
So far in this chapter we’ve seen that the course of performance improvement as a function of practice is given by the general equation у = b x m. But as useful as this equation is for describing changes in performance quality, it doesn’t tell us anything about why people get better with practice (or why, for that matter, is the learning curve steep in the beginning but gradually flattens out?). Moving from describing performance changes to explaining those changes requires that we give some attention to the nature of human memory. Figure 5.8 captures the essential idea: If experience affects “memory,” which, in turn, is related to performance, then “memory” can help us “fill in the gap” and understand why у = b x 111 (i.e., why practice is related to performance improvement).
Memory Systems: A Basic Overview
Theorists who study human memory are interested in how people acquire, store, retrieve, and utilize information they’ve gleaned from their experiences. Over the course of the last 150 years, these researchers have developed a wide array of models and theories of various memory systems (see Miyake & Shah, 1999; Tulving & Craik, 2000), but we can accomplish what we need to do here by winnowing that long history of work on memory down to just four essential concepts.
Long-Term Memory and Working Memory
Long-term memory (LTM) is a very large, relatively permanent store of information that an individual has acquired over the course of his or her lifetime. Think about all the factual information you learned in school (e.g., the state capitols, the three parts of an insect’s body), all of your knowledge of the English language (e.g., word meanings, rules of grammar), visual information (e.g., the appearance of a dachshund), motor-skill information (e.g., how to tie your shoes or ride a bicycle), and, yes, even information about the taste of chocolate ice cream. All of this, and much more, is coded in LTM. Further, evidence suggests that LTM is largely permanent. It appears that once something has been entered into LTM it stays there, even if a person can no longer recall it.
In contrast to LTM, working memory (or “short-term memory”) is a system in which a very limited amount of information is retained for brief periods (i.e., seconds). The information in working memory (WM) is generally equated with the contents of conscious awareness. In other words, we are aware of the information in WM, and this makes it quite different from the contents of LTM. You have a vast amount of information in LTM that you’re not presently conscious of. In fact, one way to think about what happens when you retrieve something from LTM is that it has been brought into WM. A simple illustration involves a piece of information that, at this moment, is in your LTM (and outside your awareness), and yet it can be brought into WM: What is your father’s middle name? As soon as the question is posed, something in the LTM system that you weren’t aware of is brought into conscious awareness, that is, into the WM system.
One other thing to note about WM is that information there can be manipulated and transformed. For example, having retrieved your father’s middle name, you can (probably) spell it backwards; having retrieved your current street address, you can find the sum of those digits; or having formed an image of your current home or apartment, you could give a “walking tour” of the place without even being there - all curtesy of WM.
A particularly important form of information manipulation in WM is rehearsal. We’ve already noted that information in WM is lost pretty quickly, but the span of retention in WM can be extended indefinitely by mental rehearsal - an unfamiliar telephone number will stay in WM as long as you choose to mentally repeat it. Of course, as long as we’re rehearsing information in WM, we’re taking up space so that other information can’t be processed there. One way to think about WM is that it is precious mental real estate - you can keep something there by rehearsal, but most of us have better things to do with our working-memory capacity than to take it up by rehearsing the same thing over and over, and once we stop rehearsing, that information will quickly pass out of WM.