3.3 Memory models, MSM

Multi-Store Memory Model

• Important theories of memory to be studied include:
  • Multi-store model of memory (MSM)
  • Working memory model
  • Long-term memory

Key Quote on Memory

• "The true art of memory is the art of attention." - Samuel Johnson

Memory Testing Activity

• Activity: Memorize a list of words in 2 minutes and then write them from memory within the next 2 minutes.
• List of Words: Nine, Swap, Cell, Ring, Lust, Plugs, Lamp, Apple, Table, Sway, Army, Bank, Fire, Hold, Worm, Clock, Horse, Color, Baby, Sword, Desk, Grab, Find, Bird, Rock
• Average Recall: 7 ± 2 items
• Extraordinary Recall: Higher than average should be considered extraordinary.

General Memory Facts

• The brain consists of about one billion neurons, each forming about 1,000 connections, totaling more than a trillion connections.
• Estimated Memory Capacity: Paul Reber suggests it can store up to 2.5 petabytes.
• Petabyte: Equivalent to 1,000,000 GB or 1,000 TB.
• Misconceptions about other species’ memory abilities like that of Dory (Blue Tang fish) are exaggerated; they do not have poor memory compared to other fish.

The Multi-Store Model Theory

• Originated in the 1950s and 1960s cognitive revolution, developed by Atkinson and Shiffrin (1968).
• Introduced the concept of different memory stores:
  • Sensory Memory
  • Short-Term Memory (STM)
  • Long-Term Memory (LTM)

Memory Stores

Sensory Registers

• Function: Store information from senses for a very brief period (~ 0.5 seconds).
• Features:
  • Modality-specific storage (taste, sight, sound, etc.).
  • Stores a vast amount of information but decays rapidly.
  • Only a small proportion transfers to STM.

Short-Term Store (Working Memory)

• Capacity: Limited to about 7 ± 2 units (Miller's magic number).
• Duration: Information lasts 15 to 30 seconds without rehearsal.
• Key Function: Acts as a rehearsal buffer; rehearsed information can transfer to LTM.
• Diagram: Recommended to support written exam answers.

Long-Term Store

• Characteristics: Holds long-term, permanent memories.
• Capacity: Unlimited.
• Storage Format: Memories are maintained as memory traces.

Attention and Rehearsal

• Attention: Necessary for transferring information from sensory registers to STM.
• Rehearsal: Essential for transferring information from STM to LTM.
  • More rehearsal strengthens the memory trace, leading to longer retention.

Search and Retrieval

• Control Processes: Retrieval of information from STM and LTM involves searching processes.
• Forgetting: Can occur not only from decay but also from search failures in locating memory traces.

Coding in Memory Stores

• Short-Term Memory (STS): Primarily uses phonetic coding (e.g., repeating words aloud).
• Long-Term Memory (LTM): Relies on semantic coding (understanding information and making meaningful connections).

Encoding Methods

1. Visual Encoding: Superficial processing focused on appearance (e.g., remembering faces).
2. Acoustic Encoding: Focus on sounds without meaningful connections (e.g., familiar melodies).
3. Semantic Encoding: Understanding meaningful connections which enrich memory storage in LTM.

Brain Structures and Memory

• Prefrontal Cortex: Associated with STM.
• Hippocampus: Related to LTM consolidation.
• Amygdala: Involved in emotional memory enhancement, boosting LTM transfer for emotionally charged experiences.

Key Study: Baddeley (1966)

Aim

• Assess whether STM & LTM coding is primarily acoustic or semantic.

Procedure

• Participants arranged words from 4 lists into correct order:
  • List A: Acoustically similar (cat, mat, sat)
  • List B: Acoustically dissimilar (pit, day, cow)
  • List C: Semantically similar (big, huge, tall)
  • List D: Semantically dissimilar (hot, safe)
• STM test: Rearranging immediate recall; LTM: 20-minute delay with interference task.

Results

• STM: List A performed worst (10% recall); Lists B, C, D performed 60-80% respectively.
• LTM: List C performed worst (55% recall); others performed better (70-85%).

Conclusions

• STM: Acoustic encoding due to confusion with similar-sounding words.
• LTM: Semantic encoding because of confusion with similar-meaning words.

Key Study Evaluation: Baddeley (1966)

• Generalization: Results applicability to wider population.
• Reliability: Can the study be repeated with consistent results?
• Ecological Validity: Does it reflect everyday behavior?
• Ethics: Adherence to ethical guidelines.

Strengths

• Aligns with real-life examples of memory use (grocery lists vs. literature).
• Supported by extensive evidence for distinct STM and LTM.

Weaknesses

• Simplistic view of memory; ignores complexity (e.g., types of LTM).
• Challenges in accurately measuring LTM capacity.
• Low ecological validity from artificial tasks in lab settings.