Fundamentals of Human Memory

Overview

Lecture explains human memory systems: sensory register, short-term (working) memory, long-term memory.
Covers attention, encoding, rehearsal, levels of processing, interference, memory types, retrieval, and mnemonic techniques.
Emphasis on practical implications for learning and remembering.

Sensory Register: initial raw, unprocessed input from senses; very brief duration.
Short-Term Memory (Working Memory): limited capacity, brief duration, active processing site.
Long-Term Memory: large (practically unlimited) capacity, long duration, more passive storage.

Maintains raw sensory information; most stimuli decay quickly unless attended.
Iconic memory (visual) lasts ~0.25 seconds; some sensory traces may last up to ~4 seconds.
Attention selects a small subset of stimuli for further processing.

Broad input but narrow processing bottleneck: attention filters which stream is processed.
Shadowing experiments: subjects attend to one ear, ignore the other; unattended channel contents often not noticed (language changes unnoticed).
Exception: highly salient information (e.g., subject's own name) in unattended channel can be detected.

Duration: about 20–30 seconds without rehearsal.
Capacity: ~7 ± 2 distinct items (George Miller, 1956).
Rapid decay and susceptible to interference.
Rehearsal maintains items; elaborative rehearsal and organization transfer items to long-term memory.
Retrieval from short-term memory often uses phonemic (sound) or structural cues.

Chunking groups multiple elements into larger meaningful units to increase effective capacity.
Example: phone numbers use dashes to form chunks.
Rehearsal: repeating items to keep them active in short-term memory.
Elaborative rehearsal: linking new material to existing knowledge to encode into long-term memory.

Processing depth influences retention: structural (shallow), phonemic (intermediate), semantic (deep).
Semantic (meaning) processing produces better long-term retention than phonemic or structural processing.
Imagery (paired with semantic processing) often produces the strongest memory (Paivio).

Proactive interference: earlier learning (A) interferes with later recall (B).
Retroactive interference: later learning (B) interferes with recall of earlier material (A).
Forgetting in short-term memory is useful: frees limited capacity for new information.
Long-term forgetting often appears as decay or retrieval difficulty; reconstruction can fill gaps inaccurately.

More passive, often unconscious, less easily disrupted.
Partially generative: retrieval often reconstructs rather than reproduces original events.
Capacity considered practically unlimited.
Encoding formats: visual imagery, verbal/semantic representations, and elaborations.
Retrieval benefits from organized knowledge structures and contextual cues.

Declarative (Explicit): episodic and semantic memory.
- Semantic Memory: knowledge of meanings, facts, concepts; stored as propositions, networks.
- Episodic Memory: memory of events tied to time/place; conveyor-belt analogy (ordered and context-rich).
Procedural (Implicit): memory for skills and actions; represented as condition-action rules (productions).
- Becomes more automatic with practice; often hard to verbalize fully.
Skills and habits are collections of procedural memories.

Propositions: smallest units of information judged true/false.
Propositional Networks: interconnected propositions; activation of one node may trigger others.
Images: mental representations preserving spatial and physical attributes.
Schemata (Schemas/Shimata): abstract data structures organizing expectations and typical features of categories or events.
- Story Grammar: schema for narrative structure; helps comprehension and memory of texts.
- Scripts/Event Schemata: typical sequence of actions for routine situations (e.g., restaurant visit).

Retrieval depends on representation, organization, and context cues.
Overlearning (practice beyond mastery) strengthens retention.
Understanding (organization and meaning) facilitates durable memory.
Relating new information to existing knowledge (elaboration) improves encoding and retrieval.
Contextual cues (time, location, environmental details) aid recall.

Method of Loci: associate items with familiar locations; use vivid, bizarre imagery at loci.
Acronyms: create initial-letter abbreviations (e.g., IBM for items).
Link (Chain) Method: form a visual or story link between successive items.
Phonetic/Keyword Method: use familiar-sounding words to anchor foreign-language vocabulary.
Vivid Visual Images: create unusual, striking images to increase memorability.
Rhymes, patterns, and standard lists (e.g., mnemonics for ordered lists) help recall.

Sensory Register: immediate, raw input store for sensory stimuli.
Iconic Memory: brief visual sensory memory (~0.25 sec).
Shadowing: attention task to follow one auditory stream while ignoring another.
Chunking: grouping elements into larger meaningful units to extend memory capacity.
Rehearsal (Maintenance): repetition to keep information active in short-term memory.
Elaborative Rehearsal: linking new information to existing knowledge for long-term storage.
Proactive/Retroactive Interference: earlier/later learning interfering with recall.
Propositions: atomic true/false information units.
Schema/Script: organized knowledge structures guiding expectation and comprehension.

Use semantic processing: focus on meaning rather than surface features.
Employ chunking for lists and numbers (phone numbers, codes).
Use elaborative rehearsal: connect new ideas to prior knowledge or examples.
Apply mnemonic methods (method of loci, acronyms, link method) for ordered or lists.
Overlearn critical material (practice beyond initial mastery) to strengthen retrieval.
Study in context-relevant environments or use contextual cues when appropriate.
Practice spaced rehearsal and repeated retrieval to combat interference and forgetting.