Memory – Comprehensive Study Notes

Learning Outcomes (LO)

• LO10.1: Describe memory & outline information-processing model

• LO10.2: Describe working memory (WM)

• LO10.3: Outline major long-term-memory (LTM) types

• LO10.4: Describe how info is encoded & organised in LTM

• LO10.5: Explain remembering, misremembering & forgetting

Key Introductory Ideas

• Memory = mental representation permitting information to re-enter mind when stimulus absent

• Representations:

  • Sensory (visual, auditory, olfactory, etc.)

  • Verbal (word-based)

  • Motoric (stored muscle movements)

• Standard computer metaphor -> three stores: Sensory Registers, Short-Term Memory (STM), Long-Term Memory (LTM)

Information-Processing / Standard Model

• Flow: Stimulus -> Sensory Registers -> (attention) STM -> (encoding) LTM -> (retrieval) STM/Consciousness

• Loss possible at every stage

• Sensory Registers: last approx 0.5 s (vision), up to 2 s (emotionally laden) - Iconic (visual) & Echoic (auditory)

• STM: 20-30 s; classic capacity 7 +/- 2 items (Miller, 1956) though modern bandwidth approx 4 or even 1 item when rehearsal/chunking prevented

• Serial Position Effect: Primacy + Recency curves

• Evolution of model:

  • Parallel vs serial processing

  • Multiple autonomous modules

  • Inclusion of unconscious/implicit systems

  • Shift of metaphor from “mind=computer” to “mind=brain”

Working Memory (WM)

• WM = active temporary storage + processing to meet goals

• Baddeley & Hitch (1974) original tripartite model; later Baddeley (2000,2010) adds episodic buffer

  • Central Executive (limited capacity control system)

  • Visuospatial Sketchpad (visual–spatial store)

  • Phonological/Articulatory Loop (verbal store)

  • Episodic Buffer (temporary multimodal integrator linked to LTM in time-sequence)

• Storage != Processing; dual-task studies show reasoning slows with high digit load (>3) but errors unchanged -> separate capacities

• Capacity correlates with fluid intelligence, academic skills, ADHD symptoms

• Neuroanatomy: Prefrontal Cortex orchestrates; posterior cortices process modality-specific info; distinct loci for object vs location memory

• Chunking -> uses LTM knowledge to compress STM load (e.g., “ASXBHPASICSMH” into ASX, BHP, ASIC, SMH)

Varieties of Long-Term Memory

• Declarative (Explicit)

  • Semantic (generic facts)

  • Episodic (autobiographical events)

• Procedural (Implicit/Skill)

• Explicit vs Implicit retrieval dimension (recall, recognition vs behavioural expression, priming)

• Everyday Memory: functional, goal-directed, meaningful; includes prospective memory (PM) – remembering to remember

  • PM types: Event-based vs Time-based cues

  • PM declines unevenly with age; aids = external reminders, exercise, mnemonic strategies

Encoding Mechanisms

• Encoding = creating retrievable code

• Levels of Processing (Craik & Lockhart 1972): Structural -> Phonemic -> Semantic (deep)

• Encoding Specificity Principle: retrieval best when context/mode matches encoding (environmental, state-dependent, mood-dependent)

• Spacing Effect: distributed rehearsal (e.g., 56-day intervals > 14-day) doubles 5-year retention

• Multimodal coding improves access; more cues

Mnemonic Devices & Study Strategies

• Method of Loci: place vivid images along familiar route

• SQ4R for textbooks: Survey, Question, Read, Recite, Review, Write

• External aids (lists, alarms); internal strategies (chunking, elaboration)

Organisation of LTM

• Networks of Association: nodes interconnected; strength varies; spreading activation (Collins & Quillian 1969)

  • Recently/frequently activated nodes possess higher baseline activation

• Hierarchical organisation: categories -> subcategories -> features (e.g., Animal -> Bird -> Canary)

• Schemas: organised knowledge structures with default values; guide encoding & reconstruction; culturally shaped

  • Can cause memory distortions (office schema experiment; typo “to to” overlooked)

Remembering, Misremembering & Forgetting

• Schacter’s “7 Sins”: transience, absentmindedness, misattribution, suggestibility, bias, persistence, blocking/forgetting

• Ebbinghaus Forgetting Curve: rapid initial loss then asymptote; mathematically logarithmic M(t) = M_0 e^(-kt)

• Causes:

  • Decay: fading synaptic traces

  • Interference: Proactive & Retroactive

  • Motivated Forgetting: goal-directed suppression (directed forgetting studies, Wegner’s thought suppression)

• Flashbulb Memories: vivid but not always accurate; dependent on adrenal arousal; propranolol blocks enhancement

• Eyewitness Testimony vulnerabilities: wording effects (“a” vs “the”), schemas, social cues; child & adult differential accuracy

• False vs Repressed Memories debate: laboratory implantation possible (approx 15%-25%); genuine abuse memories often fragmented; need balanced clinical/legal approach

Memory Across the Lifespan

• Infantile Amnesia (<2–4 yrs): linked to hippocampal neurogenesis disrupting consolidation

• Childhood elaborative parent discussions predict richer autobiographical recall later

• Ageing: Normal decline in episodic & WM; semantic & procedural relatively spared; exercise-induced neurogenesis can mitigate

Neurological Bases & Amnesia

• Medial Temporal Lobe (hippocampus) critical for consolidation of explicit memories

• Frontal Lobes: WM/executive, episodic temporal tagging

• Basal Ganglia + Cerebellum: procedural skills

• Anterograde Amnesia: cannot form new LT explicit memories (e.g., H.M. post-bilateral MTL removal) but retains implicit learning

• Retrograde Amnesia: loss of pre-injury memories (tumours, strokes, ECT)

• Alzheimer’s: severe anterograde + graded retrograde; procedural spared early, priming variable

• Huntington’s: impaired procedural, intact priming

Ethical, Philosophical & Practical Implications

• Eyewitness reliability affects justice; interview wording must avoid leading questions

• Therapy: recovered memories require corroboration; clinicians must avoid suggestion

• Education: spaced repetition, deep processing, multimodal cues improve durable learning; cumulative exams beneficial

• Cultural Relevance: mnemonics in oral cultures (e.g., Indigenous songlines) underline interplay between memory & environment

Landmark Experiments & Figures

• Ebbinghaus (1885): nonsense syllables, forgetting curve

• Sperling (1960): sensory iconic memory grid & tone

• Miller (1956): 7 +/- 2 capacity limit

• Baddeley & Hitch (1974); Baddeley (2000): WM model

• Bahrick et al. (1993): spaced language learning 5-yr retention

• Brewer & Treyens (1981): office schema false recall

• Loftus & Palmer (1974): wording effect on eyewitness speed estimates

• Cahill et al. (1994): propranolol & emotional memory

• Maguire et al. (1997,2000): London taxi drivers’ hippocampi

Selected Numerical/Statistical References

• Iconic storage duration: 0.5-2 s

• STM duration: 20-30 s without rehearsal

• Digit span: 5-9 items (classic) ; newer models approx 4

• Bahrick spacing: 13 sessions at 56-day intervals > 26 sessions at 14-day

• False-memory implantation rates approx 15%-25% over 2-3 interviews

• Grade recall study: 71% correct; 80% inflated; 6% deflated

Quick Glossary (abridged)

• STM/WM: temporary conscious store/processor

• Episodic vs Semantic: event vs factual knowledge

• Procedural: “how-to” skills

• Priming: implicit facilitation via prior exposure

• Encoding Specificity: retrieval success depends on match with encoding context

• Prospective Memory: remembering future intentions

• Chunking: grouping to expand WM capacity

• Anterograde/Retrograde Amnesia: post-/pre-injury memory loss

Study Tips Derived from Research

• Employ spaced rehearsal: review material over days/weeks

• Mix modalities: read, speak, draw, act

• Create elaborate, meaningful associations; link to prior knowledge

• Use mnemonics (method of loci, acronyms, narratives)

• Test yourself frequently (retrieval practice boosts consolidation)

• Align study context with assessment conditions when possible