Four Things You Didn’t Know About Your Brain

• Your short-term memory can only hold five to nine bits of information at a time. Any more than that, and it must be sent to long-term memory for you to handle it. That’s one reason phone numbers are only seven digits and why credit card numbers are broken into groups of four.

• Your long-term memory isn’t that reliable either. Research shows that people often misremember events they lived through. Even worse, it’s easier to come up with a memory of something that never happened, than to find one that actually did. Look at it this way. Do you really remember learning to tie your shoes — or do you just remember the story your mom tells about it?

• Your brain also uses something called sensory memory, and it’s basically an instant playback system. In other words, part of your brain can resend important information a few seconds after it was originally sent, in case you missed it the first time. That’s why you can “catch up” to what was said after you realize someone called your name and said something to you at a party, even if you were concentrating on another conversation. It’s also the reason you sometimes get déjà vu — which means “already seen.” Usually, it isn’t some phantom memory coming back to you — it’s something that just happened and your sensory memory is replaying it.

• Finally, why are your dreams so hard to remember? It turns out that the part of your brain that stores information in long-term memory shuts off while you’re asleep. So your dreams never make it out of short-term memory. That’s why most people only remember snippets of their latest dream right as they wake up and quickly forget them.