Week 8 - Long Term Memory

Long-Term Memory Overview

  • Definition: Archive of information about past events and knowledge learned.

  • Functionality: Works closely with working memory.

  • Storage Duration: Ranges from moments ago to distant memories.

    • More recent memories: More detailed.

  • Key Concepts:

    • Division of Memory Types: Distinguishing between various types of memory (episodic, semantic, procedural).

    • Interaction of Memory Types: Types interrelate and share mechanisms.

    • Overlap: Considerable overlap between different types of memory.

Types of Long-Term Memory

  • Explicit Memory: Conscious recollection of experiences and knowledge.

    • Episodic Memory: Personal experiences and events.

    • Semantic Memory: General facts and knowledge.

  • Implicit Memory: Not conscious.

    • Procedural Memory: Skills and actions (e.g., riding a bike).

    • Priming and Conditioning: Learning without conscious awareness.

Memory Retention

  • Duration: Long-term memory (LTM) retains information longer than short-term memory (STM), potentially with unlimited capacity.

  • Understanding Relationships: LTM provides background information accessed during cognitive tasks.

Serial Position Effect

  • Experiment by Murdoch (1962):

    • Purpose: Distinguishing between STM and LTM.

    • Method: Read stimulus list and recall words.

    • Results: Better recall for words at the beginning (primacy effect) and end (recency effect) of the list.

Primacy Effect

  • Definition: Better memory for first items.

  • Mechanism: Participants rehearse early items individually; first items gain full attention.

Recency Effect

  • Definition: Better memory for last items.

  • Mechanism: Items recent enough to remain in STM; susceptible to delays.

Memory Coding

  • Definition: The form in which stimuli are represented in memory.

  • Types of Coding:

    • Sensory Coding: Representation by neuron firing patterns.

    • Visual Coding: Formulating visual images in mind (e.g., recalling a friend’s face).

    • Auditory Coding: Sound representations (e.g., recalling song melodies).

    • Semantic Coding: Representing meanings and concepts.

Proactive Interference

  • Definition: Memory decline due to previously learned information interfering with new learning.

  • Implications: Especially affects groups with similar semantic categories.

Distinctions in Memory Types

  • Episodic vs. Semantic Memory:

    • Episodic: Tied to personal experiences ("self-knowing").

    • Semantic: General knowledge, does not involve time travel ("knowing").

Brain Localization of Memory

  • Patient H.M.:

    • Had hippocampus removed; retained STM but could not form new LTM.

  • Clive Wearing: Severe memory loss, lives moment-to-moment.

  • Patient K.F.: Impaired STM but functional LTM.

Double Dissociation Concept

  • Definition: Evidence of different neurological structures supporting STM and LTM.

    • Damage in one area affects one function without impacting the other.

Age and Memory Interaction

  • Impacts of Aging: Different effects on episodic and semantic memory, with structural brain changes affecting episodic recall more.

Summary of Explicit and Implicit Memory

  • Explicit: Includes episodic and semantic memory.

  • Implicit: Procedural, priming, and conditioning.

Practical Implications of Memory

  • Episodic Memory: Allows for personal time travel in memory (e.g., recalling specific events).

  • Semantic Memory: Represents general knowledge, no personal context required.