Originally published in 1978, this volume contains the evidence that is most crucial for our understanding the processes of forgetting and retention. Organized in terms of problem areas and issues that are particularly pertinent to understanding these processes, the book deals with both animal and human studies. The author begins by defining the topic and reviewing its historical development. A theoretical orientation follows, and then the author begins to address the major factors that determine what is, and what is not, remembered. Although we cannot yet specify the principles from which we can predict when an episode, once learned, will be remembered well or forgotten entirely, the author demonstrates that such principles are not that far away. He considers the issues that must be resolved before such principles are established, and in the course of doing so covers the major research on why we remember events and why they are forgotten.