Chapter 6 Notes: Memory – Remembrance of Things Past—and Future

Kinds of Memory (6-1)

• Memory systems overview

  • There are multiple memory systems, not a single database. H.M.’s case illustrates episodic memory loss after hippocampal/related damage but language, motor skills, and some implicit abilities remained intact, highlighting distinct memory systems.
  • Chapter framing: memory involves backing up information so the past isn’t lost; without memory, experience loses its meaning.

• 6-1a Explicit Memory (declarative memory)

  • Explicit memory = memory for specific information that can be clearly stated or explained.
  • Divides into two subsystems:
  • Episodic memory: memories of events that happen to us or occur in our presence; autobiographical. Examples: what you ate for breakfast, what your professor said today. Often expressed with the phrase “I remember…”.
  • Semantic memory: general knowledge and meanings; does not depend on personal experience. Examples: the United States has 50 states, who authored Hamlet. You often say “I know…” for semantic information.
  • The distinction helps explain why you might remember general facts without recalling the exact episode in which you learned them.
  • H.M. example used to illustrate explicit memory concepts (episodic/semantic) and brain regions supporting them.

• 6-1b Implicit Memory (nondeclarative memory)

  • Implicit memory = memory for how to perform tasks; the memory is demonstrated through action rather than verbal report.
  • Examples: riding a bicycle, accessing contacts, texting a message; tasks performed automatically without conscious awareness.
  • Implicit memories are suggested or implied by behavior, not verbally stated.
  • Implicit memory includes procedural memories and skill learning; can persist even when explicit memory is impaired.

• 6-1c Retrospective Memory vs. Prospective Memory

  • Retrospective memory: recalling information learned in the past (episodic, semantic, and implicit memories).
  • Prospective memory: remembering to do things in the future (e.g., pay bills, take medicine).
  • Prospective memory failures can occur when preoccupied, distracted, or stressed about time.
  • Types of prospective tasks:
  • Event-based tasks: triggered by an event (e.g., remember to take medicine with breakfast).
  • Time-based tasks: performed at a specific time (e.g., check mail at 5 PM).
  • Aging can influence retrospective and prospective memory, often slowing response rather than eliminating cue awareness; mood/depression can reduce motivation to remember intentions.

Encoding, Storage, and Retrieval (6-2)

• 6-2a Encoding

  • Encoding = transforming incoming information into a form that can be stored in memory.
  • Uses various codes:
  • Visual coding: mental pictures (e.g., representing a list as a picture).
  • Acoustic coding: sounds or phonological representations (e.g., silently reciting the items).
  • Semantic coding: meaning-based representation (e.g., forming acronyms or connecting to meanings).
  • Example with a letter list THUNSTOFAM:
  • Visual code: picture the letters.
  • Acoustic code: say them aloud in sequence.
  • Semantic/meaning code: interpret as an acronym for The United States of America (T ≈ The, H ≈ United, etc.).
  • Encoding can be enhanced by relating new information to existing knowledge (elaborative rehearsal).

• 6-2b Storage

  • Storage = maintaining information over time.
  • Includes event-based and time-based prospective memory tasks; aging can affect speed of retrieval rather than capacity alone.
  • Two key concepts:
  • Maintenance rehearsal: repeating information to keep it in working memory.
  • Elaborative rehearsal: linking new information to existing knowledge to create deeper encoding.
  • Practical tip: after encoding, strategies like semantic linking or cue-based storage improve later retrieval.

• 6-2c Retrieval

  • Retrieval = locating stored information and bringing it back to consciousness.
  • Retrieval success depends on cues and the way information was encoded.
  • If THUNSTOFAM was encoded semantically (as an acronym for The United States of America), retrieving the letters would rely on recognizing the acronym rather than decoding phonetics.
  • If retrieval cues are weak or absent, even well-encoded information may be hard to access.
  • The three-step model (encoding-storage-retrieval) explains why failures can occur at any stage.

• Notes on memory processing metaphor

  • Information processing is likened to computer memory: encoding, storage, and retrieval are stages that determine memory success.

Sensory Memory (6-3)

• 6-3a Iconic Memory (visual sensory memory)

  • Iconic memory = brief visual storage; a sensory register for visual stimuli.
  • Visual impressions are held briefly, allowing a perception to feel continuous despite rapid eye movements (saccades).
  • Duration: up to about $1 ext{ s}$ for the visual trace before it decays.
  • McDougall's early work showed limited recall with a single eye fixation; Sperling refined this with a partial-report method.

• 6-3b Iconic Memory and Saccadic Eye Movements

  • Saccadic eye movements occur about $4 ext{ times per second}$, yet iconic memory makes perception feel continuous.
  • This memory‑scan system supports seamless perception and rapid processing of moving images (e.g., film frames seeming fluid).

• 6-3c Echoic Memory (auditory sensory memory)

  • Echoic memory = brief auditory representation; holds auditory traces for several seconds (longer than iconic traces).
  • Echoic memory supports acoustic coding, which can aid retention of information presented visually when recited aloud or subvocally.

Short-Term Memory (6-4)

• 6-4a The Serial-Position Effect

  • When recalling a list, people remember the first and last items best (the primacy and recency effects).
  • Possible reasons: first items receive more rehearsal; last items remain in short-term memory as rehearsal is still active.
  • Demonstrates boundaries of short-term memory and rehearsal strategies.

• 6-4b Chunking

  • Chunking groups individual elements into larger, meaningful units to reduce cognitive load.
  • Example: THUNSTOFAM can be recalled as three chunks (THUN-STO-FAM) instead of ten separate letters.
  • George Miller argued the typical capacity of working memory is about seven chunks, +/- two.
  • Practical implication: organization into meaningful units improves memory performance.

• 6-4c Interference in Short-Term Memory (Peterson & Peterson)

  • Classic experiment: remember 3-letter sequences while counting backward, causing interference and rapid forgetting.
  • Result: new information displaces old information in STM; forgetting occurs quickly when rehearsal is blocked.
  • Implications for studying: distractions during encoding or rehearsal can significantly impair short-term retention.

• Maintenance vs elaborative rehearsal in STM

  • Maintenance rehearsal keeps information in STM for a short period; elaborative rehearsal links new information to existing knowledge for deeper encoding and easier long-term retrieval.

Long-Term Memory (6-5)

• 6-5a Accuracy and Distortions of LTM

  • Memories are reconstructive and can be biased by schemas, beliefs, and expectations.
  • Loftus highlights that memories are not perfect; memories can be shaped by cues, context, and social processes.
  • Memory is not guaranteed permanent storage; cues and encoding quality influence retrieval.

• 6-5b How much information can be stored in LTM?

  • Long-term storage capacity is effectively unlimited; the brain is capable of storing vast amounts of information over a lifetime.
  • Real-world cues are often necessary to retrieve stored information.
  • The brain’s storage is distributed across multiple cortical areas (not a single bin).
  • A penny exercise and related memory tasks illustrate how cues influence recall.

• 6-5c Levels of Processing (Craik & Lockhart)

  • Deeper (semantic, elaborative) processing yields longer-lasting memory than shallow (maintenance) rehearsal.
  • Elaborative rehearsal connects new information to existing knowledge, producing more durable memory traces.
  • Deep processing correlates with activity in the prefrontal cortex and other brain regions involved in encoding.
  • Aging and memory: older adults often show reduced depth of processing, contributing to forgetting.

• 6-5d Flashbulb Memories

  • Highly vivid, detailed memories for surprising or emotionally charged events (e.g., 9/11).
  • Factors: distinctiveness, emotional arousal, and a strong schema network surrounding the event.
  • These memories are subject to reconstruction and may become more vivid due to elaborative rehearsal and expectations.

• 6-5e Organization in Long-Term Memory

  • LTM is organized hierarchically (hierarchical structures): subordinate categories feed into broader superordinate categories.
  • Example: whales filed under mammals, which are under animals; organization supports efficient retrieval and inference.
  • Proper organization supports accurate recall and reduces errors in memory construction.
  • Flashbulb memories often create extensive networks of associations that reinforce recall.

• 6-5f The Tip-of-the-Tongue (TOT) Phenomenon

  • The experience of knowing a word but being unable to retrieve it immediately.
  • Often involves language sounds and semantic cues; partial retrieval may help guide eventual recall.
  • Causes include incomplete encoding or retrieval cues; better cues improve access to the target word.

• 6-5g The Hierarchical Structure of LTM (illustrative)

  • The chapter uses a diagrammatic hierarchy to show how information is filed (e.g., whales as mammals).
  • Highlights the importance of organization for accurate memory retrieval.

Forgetting (6-6)

• 6-6a Memory Tasks for Forgetting (Recognition, Recall, Relearning)

  • Recognition: identifying previously encountered information (easiest; multiple-choice).
  • Recall: retrieving information without cues (more difficult; relies on cues).
  • Relearning (Savings): measures how much quicker information can be learned again after a delay.
  • Bahrick’s study on college grades showed retention over decades with recognition and recall revealing forgetting patterns.
  • Savings index:
  • $ext{Savings} = N<em>{ ext{initial}} - N</em>{ ext{relearn}}$ where $N{ ext{initial}} is the number of repetitions needed originally and $N{ ext{relearn}} is the repetitions needed to relearn after a delay.

• 6-6b Interference Theory

  • Forgetting can occur because new learning interferes with old (retroactive) or old learning interferes with new (proactive).
  • Examples: learning Spanish after college French can impede recall of the French terms; vice versa is possible with similar roots.
  • Retroactive interference: new information disrupts retrieval of older material.
  • Proactive interference: older material disrupts recall of newer material.

• 6-6c Repression and Recovered Memories

  • Freud’s repression theory posits automatic exclusion of painful memories; controversial and debated.
  • Recovered memories in therapy can be unreliable; many cases involve implanted memories or schemas influencing recall.
  • Loftus and colleagues have demonstrated memory distortion under suggestion, questioning the veracity of recovered memories.

• 6-6d Infantile Amnesia

  • Inability to recall events prior to roughly age three, with fuller recall emerging later.
  • The hippocampus and limbic system development; language and cognitive development also influence early memory encoding.
  • Some memories from early childhood can be retrieved with reminders, but many are reconstructed rather than accurately remembered.

• 6-6e Anterograde and Retrograde Amnesia

  • Anterograde amnesia: inability to form new memories after a trauma; old memories may remain intact.
  • Retrograde amnesia: loss of memories prior to a trauma; some memories may be preserved while others are lost.
  • Classic H.M. case illustrates the critical role of the hippocampus in forming new episodic memories, while older procedural memories may be spared.

The Biology of Memory (6-7)

• 6-7a Neural Activity and Memory

  • Memory changes accompany neural modifications (synaptic growth, receptor changes, etc.).
  • Engrams were historically proposed as neural circuits encoding memories; modern research emphasizes distributed networks and synaptic changes.
  • Long-Term Potentiation (LTP): increased efficiency of synaptic transmission after brief, rapid stimulation; a cellular mechanism underlying learning and memory.
  • Examples in animals:
  • Sea slugs (Aplysia): conditioning increases serotonin release at specific synapses, strengthening transmission (LTP-like effects).
  • Dendritic remodeling can occur, forming new synaptic connections associated with memory storage.
  • Neurochemistry: serotonin, adrenaline, noradrenaline, acetylcholine, glutamate, vasopressin, and sex hormones influence memory processes.

• 6-7b Brain Structures and Memory

  • The hippocampus: essential for forming new memories; not a storage bin but a relay to cortex; maturation by age ~2 years relates to infantile amnesia.
  • The thalamus: involved in verbal memory formation.
  • The prefrontal cortex: executive control, supports conscious retrieval and planning, including where/when an event occurred.
  • The frontal lobes work with the hippocampus and limbic system to create a cohesive memory experience.
  • Memories are distributed across sensory cortices (visual, auditory, etc.) and integrated by the limbic system during recall.

Relationships Among Memory Types (6-5 / 6-8)

• Prospective vs Retrospective memories
  • Prospective: remembering to perform actions in the future.
  • Retrospective: recalling past events, experiences, and knowledge.
• Explicit vs Implicit memories
  • Explicit memories are conscious; implicit memories influence behavior without conscious awareness.
• Episodic vs Semantic memories
  • Episodic: personal events; location in time and space.
  • Semantic: factual knowledge and meanings; organizational networks support retrieval.

Enhancing Memory (6-6 / 6-7 / 6-8 Applications)

• Application: Using psychology of memory to improve personal memory
  • Drill and practice: repetition strengthens memory traces; useful for rote learning (e.g., alphabet, multiplication families).
  • Relating new information to what you already know (elaborative rehearsal): creates meaningful links and deeper encoding.
  • Forming unusual or exaggerated associations (mnemonics, mediators): adds distinctive cues to aid retrieval.
  • Method of loci (memory palace): linking items to be remembered to vivid locations or images (example: meat loaf in your jacket pocket to remember a shopping list).
  • Mediation: connecting items with an intermediate bridge (John → bathroom tiles → Tillie) to link names.
  • Mnemonics: acronyms and phrases such as HOMES for Great Lakes (Huron, Ontario, Michigan, Erie, Superior) or SOHCAHTOA for trigonometry relationships; can enhance recall by chunking and semantic linking.
  • Spelling mnemonics: e.g., mnemonic for spelling mnemonics (aMNesty) to remember the term itself.

Mnemonic Devices and Practice (6-7/6-8)

• Examples of mnemonic devices
  • HOMES: Huron, Ontario, Michigan, Erie, Superior (Great Lakes).
  • SOHCAHTOA: Sine = Opposite / Hypotenuse; Cosine = Adjacent / Hypotenuse; Tangent = Opposite / Adjacent.
  • Dromedary vs Bactrian camels: using D vs B to remember one-hump vs two-hump camels.
  • “Every Good Boy Does Fine”: notes on the musical staff (E, G, B, D, F).
• Summary of practical tips for studying
  • Use elaborative rehearsal to deepen encoding.
  • Create meaningful associations and vivid imagery.
  • Practice retrieval with varied cues to strengthen memory networks.

Review and Critical Considerations

• Eyewitness testimony reliability
  • Memories are reconstructive; questioning language can bias recall (Loftus studies: “smashed” vs “hit” affecting estimated speeds).
  • Children are more suggestible than adults; proper questioning can improve accuracy but biases remain.
  • Identification accuracy can be influenced by appearance cues (glasses, clothing) and context.
  • While not perfect, eyewitness testimony remains a valuable legal tool; its use should be carefully guided to minimize bias.
• Memory and memory disorders in real life
  • Repressed memories and recovered memories remain controversial; implanted memories are possible under suggestive interviewing.
  • Infantile amnesia reflects neurodevelopmental limitations (hippocampal immaturity, language development, and encoding capabilities).
• Biological basis and ethics
  • Understanding memory involves exploring neural circuits, neurotransmitters, and brain regions; advances raise considerations about memory manipulation and privacy, especially in forensic contexts.

Key Formulas and Notable Values (LaTeX)

• Savings in relearning (memory savings):
  • $ext{Savings} = N<em>{ ext{initial}} - N</em>{ ext{relearn}}$
• Iconic memory duration:
  • $ext{Iconic duration} \, \approx \, 1\ ext{s}$
• Echoic memory duration:
  • $\text{Echoic duration} \, \approx \, \text{several seconds}$
• Serial-position effect (conceptual, not a numerical formula)
• Serial processing and chunking concepts (no explicit equations, but expressed in units of chunks and time)
• Serial processing example timing (Sperling’s partial-report): presentation around $50\ \text{ms}$

Connections to broader themes:

• Memory is not a single faculty but a network of systems; understanding memory requires cross-talk between psychology, neuroscience, and cognitive science.
• The balance between encoding depth, retrieval cues, and organization determines how effectively information is stored and later retrieved.
• Ethical and practical implications of memory research affect education, the justice system, and clinical practice.