RESOURCE: How long is short-term memory? Shorter than you might think.
So, cognitive psychologists divide memory into the first 15-30 seconds, and they call this short-term memory, and alllllll the rest of memory that lasts beyond 30 seconds is long-term memory. Why would we make such a skewed split, and why aren’t there more categories (like medium-term memory)? And what good is this type of memory process, if it falls apart after much less than a minute?
You might wonder, what do we use short-term memory for? Even though short-term is very short, you are, in fact, constantly using it. You use it to remember the beginning of this sentence as you get to the end. You use it to sustain a conversation, which involves listening, formulating what you are going to say, and then saying it. You use short-term memory when you are baking, to remember the quantity of flour you need to weigh out. Your waitress will use her working memory to write down your order as you’re speaking it – but note that if she takes the whole table’s order and then goes to the machine to punch it in, she’s probably transferring your order to long-term memory!
The reason why cognitive psychologists believe that there is something truly special about the 15-30 second range that can be separated from all other memory beyond that timeframe is that patients who present with apparently total memory loss are still able to keep things in memory for 15-30 seconds.