一只耳朵进 另一只耳朵出

"We humans are pretty good at gist recall but have difficulty with being exact," he said. Though anecdotes can be told in broad outline, jokes live or die by nuance, precision and timing. And while emotional arousal normally enhances memory, it ends up further eroding your attention to that one killer frill. "Emotionally arousing material calls your attention to a central object," Dr. Schacter said, "but it can make it difficult to remember peripheral details."

As frustrating as it can be to forget something new, it's worse to forget what you already know. Scientists refer to this as the tip-of-the-tongue phenomenon, when you know something but can't spit it out, and the harder you try the more noncompliant the archives.

It's such a virulent disorder that when you ask friends for help, you can set off so-called infectious amnesia. Behind the tying up of tongues are the too-delicate nerves of our brain's frontal lobes and their sensitivity to anxiety and the hormones of fight or flight. The frontal lobes that rifle through stored memories and perform other higher cognitive tasks tend to shut down when the lower brain senses danger and demands that energy be shunted its way.

For that reason anxiety can be a test taker's worst foe, and the anxiety of a pop quiz from a friend can make your frontal lobes freeze and your mind go blank. That is also why you'll recall the frustratingly forgotten fact later that night, in the tranquillity of bed.

Memories can be strengthened with time and practice, practice, practice, but if there's one part of the system that resists improvement, it's our buffers, the size of our working memory on which a few items can be temporarily cached. Much research suggests that we can hold in short-term memory only five to nine data chunks at a time.

The limits of working memory again encourage our pattern-mad brains, and so we strive to bunch phone numbers into digestible portions and could manage even 10-digit strings when they had area codes with predictable phrases like a middle zero or one. But with the rise of atonal phone numbers with random strings of 10 digits, memory researchers say the limits of working memory have been crossed. Got any index cards?