VARIETIES OF MEMORY
So far, we’ve been discussing how memory functions and have given lit-tle attention to what was being remembered—and, to a large extent, this approach works well: The principles we’ve described apply equally to memory for word lists in the laboratory, for movies you’ve seen or songs you’ve heard, and for complex events in your everyday life. At the same time, it’s also possible to distinguish different types of memory—each with its own operating principles and its own neural basis. Let’s look at some of the crucial distinctions.
Many psychologists distinguish memory types in terms of a hierarchy like the one in Figure 8.20. On the left side of the hierarchy are the various forms of explicitmemory. These are conscious memories—memories that you can describe if youchoose—and they can usually be triggered by a direct question, such as “Do you know whether . . . ?” or “Do you recall the time when . . . ?” In contrast, implicit memories are remnants of the past that we may not recall at all, but they are (unconsciously) still with us, and we can detect these memories by the influence they still have on us. We’ll con-sider some examples of implicit memories in a moment—but, in general, these memo-ries cannot be revealed by direct questions; instead, they’re usually revealed by some sort of indirect test.