Memory Study Guide

📖 Core Concepts Memory system – an information‑processing pipeline: sensory → short‑term/working → long‑term. Sensory memory – < 1 s, automatic; includes iconic (visual) and echoic (auditory) stores. Short‑term memory (STM) – holds 4–5 items for seconds‑to‑a‑minute; capacity classic estimate $7 \pm 2$ items; relies on an acoustic code. Working memory (WM) – active manipulation of information; components: central executive, phonological loop, visuospatial sketchpad, episodic buffer. Long‑term memory (LTM) – virtually unlimited, stores information semantically; consolidation moves memories from hippocampus‑dependent to neocortical stores. Declarative (explicit) memory – conscious recall; subdivided into semantic (facts) and episodic (personal events). Non‑declarative (implicit) memory – unconscious influence; includes procedural skills, priming, conditioning. Encoding specificity & context dependence – retrieval succeeds best when cues at recall match those present during encoding. Levels of processing – deep/semantic encoding → stronger, more durable traces; shallow/surface encoding → weaker traces. --- 📌 Must Remember STM capacity: 4–5 items (modern) or $7 \pm 2$ (classic). Chunking expands STM capacity by grouping items into meaningful units. Central executive directs attention; phonological loop is disrupted by irrelevant speech. Hippocampus → essential for consolidation of new declarative memories. Long‑term potentiation (LTP) = synaptic strengthening underlying memory formation; long‑term depression (LTD) = weakening. Protein synthesis (e.g., CREB‑driven) required for long‑term memory storage. Reconsolidation: reactivated memories become labile; can be altered or erased with protein‑synthesis blockers. Interference: Retroactive – new learning impairs old. Proactive – old learning hinders new. Prospective memory: Event‑based – triggered by external cue. Time‑based – triggered by elapsed time. Sleep: Slow‑wave sleep (SWS) supports system consolidation by replaying hippocampal traces. Mnemonic aids: spacing effect, method of loci, Zeigarnik effect. --- 🔄 Key Processes Encoding → Storage → Retrieval Attention → sensory register → STM/WM → rehearsal (phonological loop) or elaborative encoding → LTM. Working Memory Updating Central executive allocates resources → phonological loop rehearses verbal info → visuospatial sketchpad stores images → episodic buffer integrates across domains → transfer to LTM. Consolidation Immediate post‑learning period: calcium influx → CREB activation → gene transcription → new protein synthesis → LTP → stable LTM. Reconsolidation (after retrieval) Retrieval → memory becomes labile → requires protein synthesis again → can be updated or disrupted. Sleep‑Dependent Consolidation During SWS, hippocampal replay → neocortical integration → long‑term stabilization. --- 🔍 Key Comparisons Declarative vs. Non‑Declarative Declarative → conscious recall (semantic, episodic). Non‑Declarative → unconscious influence (procedural, priming). Short‑Term vs. Working Memory STM – passive storage, limited duration. WM – active manipulation, includes executive control. Proactive vs. Retroactive Interference Proactive – old info blocks new learning. Retroactive – new info erodes old memory. Event‑Based vs. Time‑Based Prospective Memory Event‑based – cue is external (e.g., “when you see the mail”). Time‑based – cue is internal clock (e.g., “at 3 pm”). Deep vs. Shallow Encoding Deep – focus on meaning → durable trace. Shallow – focus on surface features → fragile trace. --- ⚠️ Common Misunderstandings “Rehearsal is the only way to get into LTM.” – Evidence shows semantic encoding and emotional arousal can also produce LTM without explicit rehearsal. “Sensory memory is the same as STM.” – Sensory memory is pre‑attentive, lasts < 1 s; STM holds information after attention is directed. “All memories are stored the same way.” – Declarative vs. procedural memories rely on different neural circuits (hippocampus vs. basal ganglia/cerebellum). “Stress always improves memory.” – Acute stress can enhance encoding of emotional items but impairs retrieval and chronic stress damages hippocampal neurons. --- 🧠 Mental Models / Intuition “Memory as a library.” Sensory traces are like books on the checkout desk; STM is the reading table (few books at a time); WM is the research assistant that pulls, rearranges, and integrates information; LTM is the shelves where books are cataloged semantically. “Encoding specificity = matching key‑card.” The cue at retrieval must fit the same lock (key‑card) used during encoding. --- 🚩 Exceptions & Edge Cases Highly rehearsed procedural skills are less susceptible to reconsolidation disruption. Flashbulb memories feel vivid but are not immune to distortion; emotional arousal boosts encoding but not accuracy. Aphantasia impairs the visuospatial sketchpad but leaves phonological loop intact. --- 📍 When to Use Which Chunking → use when STM load > 4 items (e.g., remembering a phone number). Method of loci → best for ordered lists or unrelated items (leverages spatial memory). Spacing → schedule multiple short study sessions rather than one marathon. Context‑matching → study in an environment similar to the test setting to boost retrieval. Dual‑task design → predict easier performance when tasks use different WM subsystems (verbal + visual). --- 👀 Patterns to Recognize “Cue‑dependent retrieval” questions often mention identical study‑test environments → answer: Encoding specificity. “Interference” scenarios: newer list presented after older → expect retroactive interference. “Prospective memory” prompts with time vs. event cues → choose time‑based or event‑based strategies accordingly. “Sleep deprivation” → expect poorer consolidation and increased false memories. --- 🗂️ Exam Traps Distractor: “STM stores information acoustically only.” – Wrong; while acoustic coding dominates, visual information can also be stored briefly. Distractor: “The hippocampus is needed for procedural memory.” – Incorrect; procedural memory relies on basal ganglia/cerebellum. Distractor: “All memories become permanent after consolidation.” – False; memories can still be altered via reconsolidation or interference. Distractor: “Flashbulb memories are always accurate.” – Misleading; they are vivid but not necessarily accurate. Distractor: “Chunking works for any type of material.” – Overgeneralization; effective mainly when meaningful groupings exist. ---