How does memory work, from short-term to long-term?
Memory works in three steps: encoding gets information in, storage keeps it, and retrieval gets it back out. What you attend to enters short-term memory, deeper processing moves it into long-term memory, and each successful retrieval makes it easier to find again.
The stages: sensory, short-term, long-term
The Atkinson-Shiffrin model is the version most courses start with. Sensory memory holds a brief, detailed trace of what you saw or heard, for under a second for images and a few seconds for sounds. What you pay attention to moves into short-term memory, which holds only a few items (Miller's classic estimate was about seven; later work suggests closer to four chunks) and loses them within seconds unless you keep them active.
Baddeley's working memory model refines the short-term stage: it is a workspace with separate parts for sounds and for visual and spatial information, run by a central executive that directs attention.
Long-term memory has no practical capacity limit. It splits into explicit memory (facts and events you can state) and implicit memory (skills and conditioned responses, like those in classical conditioning). The hippocampus is central to forming new explicit memories, which is why the patient H.M. could not form new ones after it was removed.
Encoding and retrieval
How you encode something decides how well it lasts. Maintenance rehearsal, repeating a phone number, holds it briefly. Elaborative rehearsal, linking it to meaning and to what you already know, encodes it deeply. Over time, memories are consolidated, partly during sleep. At the cellular level this involves strengthened connections between neurons.
Retrieval depends on cues. Recognition (multiple choice) is easier than recall (free response) because the cue is in front of you. You also remember better in the context or state you learned in. Forgetting is often a retrieval failure or interference: old learning blocking new is proactive interference, new blocking old is retroactive.
Common exam mistakes
- Mixing up proactive and retroactive interference. Pro means forward: the old memory interferes with the new one.
- Placing all memory in the hippocampus. It helps form explicit memories; skill memories rely on structures such as the cerebellum and basal ganglia.
- Treating rereading as studying. Familiarity is not the same as being able to retrieve.
Using this when you study
Two of the most reliable findings in learning science are the spacing effect (review spread out beats one long session) and the testing effect (pulling an answer from memory strengthens it more than rereading). Ebbinghaus's forgetting curve shows why spacing helps: you forget fastest soon after learning.
In Isotoon, you can ask "How does memory move from short-term to long-term?" and get a short video of each stage. The notebook then lists each video to rewatch 1, 3, 7, 14 and 30 days after you made it. Rewatching on that schedule gives you the spacing; for the testing effect, try to explain the idea out loud before you press play. Our guide on studying without forgetting goes further, and AP Psychology covers the rest of the unit.
Questions
- How long does short-term memory last?
- Without rehearsal, information in short-term memory fades within seconds, usually well under a minute. Rehearsing it keeps it active, and connecting it to meaning helps move it into long-term memory.
- What is the difference between recall and recognition?
- Recall means retrieving information with few cues, as on a fill-in-the-blank or essay question. Recognition means identifying information you see, as on a multiple-choice question. Recognition is usually easier.
- Does sleep help memory?
- Yes. Sleep supports consolidation, the process that stabilizes new memories, so sleeping after studying generally helps you keep what you learned better than staying up.