Analyze encoding, storage, retrieval, working memory, long-term memory, forgetting, interference, and memory construction.
A lesson of AP Psychology, in Learning, Cognition, Memory, and Language, about 10 minutes.
By the end of this lesson, you will be able to describe the Atkinson-Shiffrin model of memory, explain encoding, storage, and retrieval processes, and analyze why memory fails and how to improve it.
Models of Memory
Atkinson-Shiffrin Three-Stage Model
Stage 1 — Sensory Memory:
Holds sensory impressions briefly (fractions of a second to 2 seconds)
Most sensory information is not attended to and fades
Stage 2 — Short-Term Memory (STM) / Working Memory:
Information that is being actively processed right now
Capacity: Miller's Law — "7 ± 2 chunks" of information
Duration: about 20–30 seconds without rehearsal
Rehearsal: actively repeating information keeps it in STM and can transfer it to LTM
Working memory model (Baddeley): STM is not just storage — it is active processing; includes the phonological loop (verbal/auditory), visuospatial sketchpad (visual/spatial), episodic buffer (integrates information), and central executive (directs attention)
H.M. (Henry Molaison): hippocampus removed for epilepsy; could not form new explicit memories (anterograde amnesia) but could still learn new motor skills (implicit memory intact). Revealed the distinction between explicit and implicit memory.
Encoding
Encoding is converting information into a form the memory system can process.
Automatic processing: some information is encoded without effort (routine activities, locations, time, frequency).
Structural (shallow): how does the word look? — weakest encoding
Phonemic (intermediate): how does the word sound?
Semantic (deep): what does the word mean? — strongest, most durable encoding
Encoding strategies:
Chunking: organizing information into meaningful units (SSN as 3 chunks, not 9 digits)
Mnemonics: memory tricks (ROY G BIV for colors of the spectrum)
Method of loci (memory palace): associating items with locations on a familiar path
Spacing effect (distributed practice): studying spread over time is more effective than massed practice (cramming)
Self-reference effect: encoding information in relation to yourself improves retention
Testing effect: actively retrieving information (practice testing) is more effective than rereading
Storage and the Role of the Hippocampus
Consolidation: the process by which short-term memories are converted to long-term memories; occurs during sleep (memory consolidation during sleep is well-established).
Hippocampus: essential for forming new explicit long-term memories; damage → anterograde amnesia (cannot form new memories). Procedural and emotional memories don't require the hippocampus.
Amygdala: enhances memory for emotionally arousing events; flashbulb memories (vivid memories of highly emotional events — JFK assassination, 9/11) involve the amygdala.
Retrieval
Recall: reproducing information without cues (essay questions).
Recognition: identifying previously encountered information (multiple choice).
Relearning: how much faster you learn something the second time (even without conscious recall).
Retrieval cues: stimuli associated with the memory that help bring it back.
Context-dependent memory: recall is better when the context at retrieval matches the context at encoding (encoding specificity principle). Divers who learned words underwater remembered them better underwater.
State-dependent memory: recall is better when internal state at retrieval matches state at encoding (drunk learning recalled better while drunk).
Encoding failure: information never made it into LTM ("I don't remember meeting you" — never encoded the face).
Decay (Ebbinghaus forgetting curve): memories weaken over time without use. The "forgetting curve" — rapid initial forgetting, then slower decline. Ebbinghaus (1885) documented this with nonsense syllables.
Interference:
Proactive interference: old memories interfere with new ones (learning Spanish hinders learning French)
Retroactive interference: new memories interfere with old ones (learning French makes you forget Spanish)
Retrieval failure: the information is stored but cannot be accessed (tip-of-the-tongue phenomenon).
Motivated forgetting / Repression: Freudian concept — anxiety-laden memories pushed into the unconscious. Limited scientific support; false memory research challenges this.
Memory Construction and Misinformation
Memory is not a recording — it is a reconstruction. Each time we recall a memory, we partially rebuild it, leaving it susceptible to alteration.
Elizabeth Loftus and the misinformation effect: post-event information can alter memories of an event. "About how fast were the cars going when they smashed?" → higher speed estimates and more likely to report broken glass than "hit" condition. Huge implications for eyewitness testimony.
Source monitoring errors: forgetting where a memory came from; can lead to cryptomnesia (believing a borrowed idea is original) or false familiarity.
Imagination inflation: imagining an event increases confidence that it happened.