The bombing of Pearl Harbor, the assassination of President Kennedy, the explosion of the space shuttle Challenger: every generation has unforgettable events, the shared memory of which can create fleeting intimacy among strangers. These public memories, combined with poignant personal moments--the first day of college, a baseball game with one's father, praise from a mentor--are the critical shaping events of individual lives.

Although experimental memory studies have long been part of empirical psychology, and psychotherapy has focused on repressed or traumatizing memories,...