So / how accurate / are / our memories? / It depends on / which kind of memory / we're talking about. // There are three / kinds of long-term memory. // There's semantic memory. // Semantic memories are / the facts / and data, / the information you learned in school,/ six times six,/ who was the first president, / that kind of information. // Also, / your biographical information, / where you were born,/ your street address, / your phone number./ So if we're talking about semantic memory, / that's pretty stable / and accurate. / For example, / if you learned that / six times six is 36, / when you were in the third grade, / you're not gonna / suddenly / misremember that decades later as / six times six / is 75. / That's not going to happen.// There's also / muscle memory. / Muscle memory / is similarly stable / over time. / It's a little bit of a misnomer /. Muscle memory / doesn't live in your muscles./ This actually / lives in a part of your brain / called the motor cortex. / That part of your brain / tells all of the voluntary muscles in your body what to do.// Muscle memory is / the memorized choreography, / the procedure for how to do things /- how to brush your teeth / how to swing a golf club, / how to eat / an ice cream cone. / This is where the expression / "just like riding a bike comes in",/ right? / You can not ride a bike for decades / and then get back on the bike / and your brain will / remember the choreography. / You'll get on the bike and ride.// Episodic memory is a little different. / This is your memory for the stuff that happened./ This is the story of your life./ This is, "oh, remember when." // That's a little strange. / It turns out that every time we recall a memory / for something that happened, / we have the opportunity to change it. / Often not consciously. / We might add a detail./ We might leave a detail out./ If somebody else experienced/ the same / event, / they might add some information that we agree with. / And so we'll add that to our memory./ We're also as human beings, / natural born storytellers. / So if there are / pieces of information missing in my story / or if there's a way / I could embellish / and make the story better, / give it a nice beginning, / middle / and end, / I might supply that /, not knowing / that I'm consciously lying./ I'm just providing information / that makes sense, / to tell you the story of what happened.//