Where'd We Leave That Darn Fact?

Semantic memory helps us recite the multiplication tables. Episodic memory is more personal. The duct tape is in the hall closet, sweetie!

A memory passes through several stages, including perception, storage and retrieval.

Information is taken into the brain through the senses. It is stored in or near the hippocampus for a few years, Ullman says, then it resides in the neocortex. The hippocampus, a Greek word for a mythical seahorse, is a portion of the limbic system in the middle of the brain. If the hippocampus is damaged -- by stress, trauma or lack of oxygen -- short-term memories may be harmed. The neocortex is the outside part of the brain. As we get older, memories are harder to find on those cortex shelves.

Why do we remember some things and forget others?

Paying attention, says Ullman -- echoing Dr. Johnson -- is the best method of remembering. Frequency helps. For example, if you hear a word often enough, you learn it. And if a piece of information fits neatly into your worldview, he says, it's easier to recall.

If a memory "has significance to us," says Otto H. MacLin, a psychology professor at the University of Northern Iowa, who studies memory and the law, "we tend to remember it better."

George C. Leal, a commercial litigator in San Francisco, was in town recently observing the Libby trial from the back of the courtroom. "What is locked into the cerebral cortex of a witness is sometimes the best evidence and only evidence available to prove a point," he says. Strength of memory "is directly tied to the level of importance to the person who is doing the remembering."

Not paying attention can be humiliating. We ask someone about her father only to be reminded that he died several years ago. And we were at the funeral. We have to be introduced to the same person every time we meet them. The vice president tells us something and we forget it. But we remember distinctly what Tim Russert of NBC's "Meet the Press" tells us.

Why do we embellish memories?

Memory is a malleable thing. We have all strata of memories -- good, bad, vivid, vague, distinct, distant. There are those who believe that some memories are repressed and recovered; others believe that those memories are imagined.

Memory, according to Oscar Wilde, "is the diary that we all carry about with us." And our memories are just that -- ours.

Authors of memoirs have made millions. Frank McCourt's "Angela's Ashes" and Elizabeth Kim's "Ten Thousand Sorrows" were challenged as being factually imprecise. Imprecision, however, seems different from James Frey's "A Million Pieces," based on his remembrances of the lowlife. After selling several million copies he admitted he had made up large parts of it. Some embellishment of memory is a natural desire. To make a better story and, memory researchers say, to fill in blanks.