# Memory Memory is the cognitive faculty that encodes, stores, and retrieves information—the foundation of learning, identity, and intelligent behavior. Modern memory research began with Hermann Ebbinghaus's 1885 studies of forgetting curves and was transformed by the "cognitive revolution" and neuroscience discoveries. Key contributions include [[George Miller]]'s working memory limits ("magical number 7±2"), the Atkinson-Shiffrin multi-store model, and Endel Tulving's distinction between episodic and semantic memory. Memory is not a single system but a collection of distinct processes and brain regions. [[Working Memory]] holds information for immediate use; long-term memory stores knowledge and experiences potentially for life. Encoding transfers information from short to long-term storage; retrieval brings it back. Memory is reconstructive, not reproductive—we don't replay recordings but rebuild experiences, making memory susceptible to distortion. Understanding memory has applications in education (spaced repetition), [[Personal Knowledge Management (PKM)]], and treating disorders like amnesia and PTSD. ## Memory Systems ``` ┌─────────────────────────────────────────────────────────────┐ │ MEMORY SYSTEMS │ ├─────────────────────────────────────────────────────────────┤ │ │ │ SENSORY MEMORY (milliseconds-seconds) │ │ ├── Iconic (visual) │ │ └── Echoic (auditory) │ │ │ │ │ ▼ │ │ SHORT-TERM / WORKING MEMORY (seconds-minutes) │ │ └── Limited capacity (~7 items) │ │ │ │ │ ▼ (encoding) │ │ LONG-TERM MEMORY (days-lifetime) │ │ ├── EXPLICIT (Declarative) │ │ │ ├── Episodic (events, experiences) │ │ │ └── Semantic (facts, concepts) │ │ └── IMPLICIT (Non-declarative) │ │ ├── Procedural (skills, habits) │ │ ├── Priming (perceptual facilitation) │ │ └── Conditioning (learned associations) │ │ │ └─────────────────────────────────────────────────────────────┘ ``` ## Memory Processes | Process | Description | Example | |---------|-------------|---------| | **Encoding** | Transform input into memory trace | Studying for exam | | **Storage** | Maintain information over time | Consolidation during sleep | | **Retrieval** | Access stored information | Recalling answer on test | | **Forgetting** | Loss of access to information | Decay, interference | ## Types of Long-Term Memory | Type | Description | Brain Area | Example | |------|-------------|------------|---------| | **Episodic** | Personal experiences | Hippocampus | Your last birthday | | **Semantic** | Facts and concepts | Temporal cortex | Paris is France's capital | | **Procedural** | Skills and habits | Basal ganglia, cerebellum | Riding a bicycle | | **Priming** | Facilitated processing | Cortical areas | Word completion | ## Forgetting Curve (Ebbinghaus) ``` Retention 100% │● │ ● │ ● │ ● 50% │ ●─────●───────●────────● │ 0% └─────────────────────────────────── Time Day 1 Day 2 Week Month Rapid initial forgetting, then slower decline Spacing effect: distributed practice improves retention ``` ## Memory Enhancement Strategies | Strategy | Mechanism | |----------|-----------| | **Spaced repetition** | Distributed practice strengthens retrieval | | **Elaboration** | Deep processing creates more connections | | **Chunking** | Group items to overcome capacity limits | | **Method of loci** | Spatial associations aid retrieval | | **Retrieval practice** | Testing strengthens memory | | **Sleep** | Consolidation occurs during sleep | | **Interleaving** | Mixing topics improves discrimination | ## Key Figures | Person | Contribution | |--------|--------------| | Hermann Ebbinghaus | Forgetting curve, nonsense syllables | | [[George Miller]] | Working memory capacity (7±2) | | Atkinson & Shiffrin | Multi-store model (1968) | | Endel Tulving | Episodic vs semantic memory | | Alan Baddeley | Working memory model | | Elizabeth Loftus | False memories, eyewitness unreliability | ## Memory Distortions | Distortion | Description | |------------|-------------| | **False memories** | Remembering events that didn't occur | | **Source confusion** | Misattributing where information came from | | **Misinformation effect** | Post-event information alters memory | | **Hindsight bias** | "I knew it all along" | | **Rosy retrospection** | Past seems better than it was | ## References - Baddeley, A. (2012). "Working Memory: Theories, Models, and Controversies" - https://en.wikipedia.org/wiki/Memory ## Related - [[Working Memory]] - [[Cognitive Psychology]] - [[Cognitive Science]] - [[George Miller]] - [[Spaced Repetition]] - [[Personal Knowledge Management (PKM)]]