ABSTRACT
As the previous chapters in this book make abundantly clear, the subject of forgetting is as multifaceted as it is enigmatic. Why, exactly, do we forget? As noted by Levy, Kuhl, and Wagner (this volume, Chapter 7) we often use the term “forget” to refer to the inability to retrieve information that we failed to encode in the first place. Thus, for example, I might say that I forgot where I placed my keys, but the truth may be that I set them down without ever taking note of the fact that I put them on the kitchen counter. Although such absent-mindedness is an interesting issue in its own right, when experimental psychologists and cognitive neuroscientists study forgetting, they usually study the loss of information that was encoded, as shown by the fact that the information was once retrievable from long-term memory. What is it about the passage of time that renders once retrievable information ever more difficult to remember? That is the question I consider in this chapter.
