Memory Systems and Models: Atkinson-Shiffrin, Sensory, Short-Term, and Long-Term Memory

Memory

Information-Processing Model of Memory

The Information-Processing Model of memory, proposed by Atkinson and Shiffrin (1968), likens human memory to a computer system, emphasizing the processes of encoding, storage, and retrieval. This model describes how information moves through different stages of memory.

• Encoding: The process of converting sensory input into a form that can be stored in memory.

• Storage: The retention of encoded information over time.

• Retrieval: The process of accessing stored information when needed.

Computer Analogy: Memory is conceptualized as a system with input (encoding), processing (storage), and output (retrieval).

Sensory Memory

Sensory Memory is the initial stage of memory, responsible for briefly holding information from the sensory systems (e.g., sight, sound, touch). Sensory memory has a very large capacity but retains information for only a fraction of a second.

• Iconic Memory: Visual sensory memory, lasting about 0.5 seconds.

• Echoic Memory: Auditory sensory memory, lasting about 2-4 seconds.

• Haptic Memory: Tactile sensory memory.

Support: Sperling's experiment (1960) demonstrated the large capacity and brief duration of iconic memory by showing participants could recall more letters when cued immediately after presentation.

• Eidetic Images: Rare ability to retain detailed visual images for longer periods (sometimes called photographic memory).

Type	Duration	Capacity
Iconic	0.5 sec	Very large
Echoic	2-4 sec	Very large
Haptic	~2 sec	Very large

Example: The Sperling experiment used a grid of letters flashed briefly, followed by a tone to cue recall of a specific row.

Short-Term Memory (STM) and Working Memory

Short-Term Memory (STM) is the system that temporarily holds and processes information in our conscious awareness. Working Memory is a more modern concept, emphasizing the active manipulation of information.

• Phonological Loop: Maintains language-based information for a short time.

• Rehearsal: Repeating information to keep it in STM; can be disrupted by distractions.

• Capacity: STM is limited to about 7 ± 2 items (Miller's Law).

• Chunking: Grouping information into larger, meaningful units to expand STM capacity.

Component	Function
Central Executive	Directs attention and coordinates subsystems
Phonological Loop	Processes verbal and auditory information
Visuospatial Sketchpad	Processes visual and spatial information

Example: Remembering a phone number by grouping digits (e.g., 555-1824).

Formula:

$\text{STM Capacity} = 7 \pm 2 \text{ items}$

Long-Term Memory (LTM)

Long-Term Memory is the system for storing information over extended periods. LTM has a virtually unlimited capacity and duration.

• Retrieval Cues: Stimuli that help access information in LTM.

• Tip-of-the-Tongue Phenomenon: Temporary inability to retrieve information, often due to insufficient cues.

• Reinstating the Context: Returning to the environment or context where learning occurred can aid retrieval.

Example: Remembering a word after being given a related cue.

Memory Construction and Reconstruction

Memory is not a perfect recording; it involves construction and reconstruction, influenced by prior knowledge and expectations.

• Schemas: Cognitive frameworks that help organize and interpret information.

• Bartlett (1932): Demonstrated that recall is shaped by cultural schemas.

• Loftus & Palmer (1974): Showed that leading questions can alter eyewitness memory.

Example: Participants recalling a story may change details to fit their expectations.

Forgetting

Forgetting refers to the loss or inability to retrieve information from memory. Several mechanisms explain why forgetting occurs.

• Interference: New or old information disrupts recall.

• Retrieval Failure: Inability to access stored information due to lack of cues.

• Intentional Forgetting: Deliberate suppression of memories.

• Decay: Fading of memory traces over time due to lack of use.

Recovered Memories: Memories that were repressed and later recalled, often controversial in legal contexts.

Encoding and Attention

Encoding is the process of converting information into a form that can be stored in memory. Selective attention determines which sensory information is encoded.

• Stroop Test: Demonstrates the effect of selective attention by requiring participants to name the color of a word rather than the word itself.

Example: Focusing on a lecturer's voice in a noisy classroom.

Levels of Processing Theory

The Levels of Processing Theory suggests that the depth of processing affects how well information is encoded and retained.

• Deep Processing: Involves semantic associations and leads to better retention.

• Shallow Processing: Involves surface features (e.g., appearance, sound) and leads to poorer retention.

Criticisms: The theory is sometimes criticized for being vague about what constitutes 'depth' and for not accounting for all encoding differences.

Mnemonic Devices and Elaborative Encoding

Mnemonic devices are strategies that aid memory by organizing information.

• Elaborative Encoding: Linking new information to related ideas or facts.

• Imagery: Associating information with visual images.

• Self-Referent Encoding: Relating information to oneself to enhance retention.

Example: Using acronyms or rhymes to remember lists.

Additional info: The notes have been expanded with definitions, examples, and context for clarity and completeness.