Comprehensive Memory Lecture Notes

Definition of Memory

• Memory = the ability to store and retrieve information over time.
• Can be described from three complementary perspectives:
  • As Stages: \text{Encoding} \rightarrow \text{Storage} \rightarrow \text{Retrieval}
  • As Types: Explicit vs. Implicit
  • As Systems: Sensory, Short-Term, Long-Term

Atkinson–Shiffrin / Multi-Store Model

• Proposes three structurally distinct memory systems working in sequence:
  • Sensory Memory (SM)
  • Short-Term Memory (STM)
  • Long-Term Memory (LTM)
• Each store differs in duration, capacity, and form of coding.

Sensory Memory (Images & Echoes)

• First stop for incoming sensory data.
• Holds raw sensory information for fractions of a second up to several seconds.
• Acts as a brief buffer so that attention can select information for further processing.

Short-Term Memory (STM) & Working Memory (WM)

• Duration: more than a few seconds but usually < 1 min.
• Capacity: small (classically ~7±2 items, though not explicitly stated in transcript).
• Information here is temporary and requires rehearsal or elaboration to survive.
• Working Memory = the set of processes that actively hold & manipulate STM contents for complex cognition (learning, reasoning, comprehension).
• Distinction:
  • STM = passive brief store.
  • WM = active processing/manipulation layer atop STM.

Long-Term Memory (LTM)

• Relatively permanent, virtually unlimited capacity.
• Stores names, phone numbers, life events, etc.
• Two major subdivisions:
  • Explicit (Declarative) Memory – “Knowing What”
  • Requires conscious awareness & intentional recall.
  • Measured by asking a person to consciously remember.
  • Two forms:
    • Episodic: personal experiences (e.g., high-school graduation).
    • Semantic: facts & general knowledge (e.g., definition of "affect").
  • Implicit (Procedural) Memory – “Knowing How”
  • Does not require conscious awareness.
  • Revealed via influence on behaviour/performance.
  • Three forms:
    • Procedural Memory: motor & cognitive skills (e.g., riding a bike, dialling a phone). Often "unexplainable"—must be learned by doing.
    • Classical-Conditioning Effects: learned associations.
    • Priming: exposure enhances identification of objects/words later.

Mental Representation Examples

• Diagram used in slides (verbal description):
  • Explicit → Semantic (facts) & Episodic (events)
  • Implicit → Procedural (skills), Priming, Classical Conditioning

Core Memory Processes

1. Encoding
   • Transforming sensory input into a form suitable for storage.
   • Selective: we tend to encode what seems relevant.
2. Storage
   • Maintaining encoded information over time.
   • Requires physiological change = consolidation.
3. Retrieval
   • Bringing stored information back to conscious awareness.

Seven Sins / Error Types in Memory

• Transience (Forgetting): accessibility decreases with time (e.g., plot of a long-ago movie).
• Blocking (Forgetting): information present yet temporarily inaccessible (tip-of-tongue; forgetting a person’s name).
• Absent-Mindedness (Forgetting): lapse due to inattention (losing keys, phone).
• Persistence (Undesirable/Intrusion): unwanted memories resurface (embarrassing faux pas, trauma).
• Misattribution (Distortion): assign memory to wrong source (crediting the wrong friend).
• Suggestibility (Distortion): memory altered by misleading info (false memories of events that never happened).
• Bias is implied though not fully detailed on slide—overlaps with distortion category.

Real-World Illustrations of Memory Distortion

• DC Sniper Case (2002)
  • Hotline received 140 000 tips; focus on a white van after publicised eyewitness report.
  • Suspects ultimately found in a blue sedan → shows power of suggestibility.
• Eyewitness Misidentification – Ronald Cotton Case (1984)
  • Victim’s confidence grew from uncertainty (“looks most like…”) to complete certainty through police feedback.
  • Cotton served 11 years; exonerated by DNA.
  • Demonstrates dangers of suggestive identification procedures (e.g., line-up bias, confirming feedback).
• Misinformation Effect – Loftus & Palmer (1974)
  • 45 students viewed car-crash films.
  • Different verbs (“smashed”, “collided”, “bumped”, “hit”, “contacted”) altered speed estimates.
  • One-week follow-up: “Smashed” group >2× more likely to "remember" non-existent broken glass.
  • Shows that post-event wording can implant false details.

Causes of Forgetting

• Encoding Failure: information never entered LTM.
• Consolidation Failure: disruption prevents permanent trace.
• Motivated Forgetting: suppression/repression of painful or guilt-producing material.
• Decay: unused traces fade over time.
• Interference: similar info competes.
  • Proactive Interference (PI): old info hinders new (old Gmail password \rightarrow can’t recall new one; French study hampers Spanish test).
  • Retroactive Interference (RI): new info hinders old (new college email makes you forget old address; Spanish study hampers earlier French test).
  • Interference stronger when contents are similar.

Strategies & Techniques to Increase Memory

• Elaborative Rehearsal
  • Deep processing; link to existing knowledge.
  • Example: picture a “hippopotamus with great memory” to encode “hippocampus”.
• Self-Reference Effect
  • Tie material to personal experience for stronger encoding.
• Forgetting Curve Awareness
  • Rapid initial loss; review right before test to refresh traces.
  • Overlearning helps prevent storage decay.
• Spaced Repetition (Spacing Effect)
  • Study in multiple, distributed sessions → better long-term retention.
• Rehearsal & Testing
  • Organise notes, take practice quizzes, link new with known.
• Minimise Interference
  • Study in quiet, low-distraction environments.
• Physical Exercise
  • Regular movement enhances cognitive function & brain health.
• Adequate Sleep
  • Essential for consolidation; sleep loss impairs encoding & retrieval.
• Mnemonic Devices
  • Acronyms (POV = Point of View).
  • Acrostics ("My Very Educated Mother Just Served Us Nine Pizzas" → planets + dwarf planet order).
• Context-Dependent Retrieval
  • Recall improves when learning & testing contexts match (e.g., study in exam-like conditions).
• Continual Practice After Mastery (Overlearning)
  • Keeps information accessible even under stress.

Quick Study-Technique Reference (from Slide Table)

• Self-Reference: "I once experienced a tip-of-the-tongue…" → anchor concept.
• Forgetting Curve: last-minute re-review boosts retention.
• Spacing Effect: small daily sessions beat cramming.
• Overlearning: study beyond “I know it”.
• Context-Dependent Retrieval: replicate exam conditions when studying.

Concept Integration & Ethical Implications

• Accurate memory is foundational in legal contexts (eyewitness testimony). Understanding suggestibility and misinformation can prevent wrongful convictions.
• Knowledge of memory fallibility reminds clinicians (e.g., in recovered-memory therapy) to avoid inadvertently implanting false memories.
• Educators can harness elaborative rehearsal, self-reference, and spacing for curriculum design.

Consolidated Model Snapshot

(\text{Sensory} \xrightarrow{attention} \text{STM/WM} \xrightarrow{encoding} \text{LTM} \xrightarrow{retrieval} \text{Conscious Recall})