Short-term vs long-term memory: the differences explained
One holds a phone number for a few seconds. The other holds your childhood. Here’s how they differ, and how information makes the jump.
Psychologists have long described memory as a system with several parts. The two most famous are short-term and long-term memory. They work very differently, and knowing the difference explains a lot of everyday forgetting.
Short-term memory
How much: a handful of items, famously “seven, plus or minus two”, and closer to four chunks by more recent estimates. How long: seconds. Classic experiments found that when people were prevented from rehearsing, letters were largely forgotten within about 20 seconds. How it’s kept: by rehearsal, like repeating a phone number in your head.
A closely related idea is working memory: short-term memory plus the ability to work with what’s in it.
Try it: this quick test measures how much your short-term memory holds.
Long-term memory
How much: no known limit in practical terms. How long: from hours to a lifetime. How it’s organized: by meaning and connections, not just in order.
Long-term memory has several kinds: episodic (events you experienced), semantic (facts and knowledge) and procedural (skills, like typing or cycling).
Side by side
- Capacity: short-term, a few chunks; long-term, vast.
- Duration: short-term, seconds; long-term, up to a lifetime.
- Forgetting: short-term, by fading or being pushed out; long-term, mostly by retrieval failure and interference.
- Example: short-term, a code you just read; long-term, your own phone number.
How information makes the jump
Attention: nothing is stored if it isn’t noticed. Meaning: connecting new information to what you know helps it stick. Repetition and review, ideally spaced out; see spaced repetition. Sleep, which helps consolidate new memories; see sleep and memory.
Why this matters day to day
Most “I have a terrible memory” moments are short-term memory doing exactly what it’s designed to do: letting go of things you didn’t mark as important. If you want something to last, give it attention and a reason to stay.
Frequently asked questions
What is the difference between short-term and long-term memory?
Short-term memory holds a small amount of information for seconds unless you keep rehearsing it. Long-term memory holds a vast amount of information for years.
How long does short-term memory last?
Without rehearsal, information in short-term memory fades within seconds, often in under half a minute.
How does information move into long-term memory?
Through attention, meaningful processing, rehearsal and review, and consolidation, much of which happens during sleep.