Memory Models and Forgetting

Multi-Store Model of Memory (Atkinson & Shiffrin)

  • Groundbreaking Structure: This model provides a very structured way to understand the flow of information through the memory system.

  • Components: The model consists of three main stores:

    • Sensory Register

    • Short-Term Memory (STM)

    • Long-Term Memory (LTM)

  • Information Flow Example (Phone Number):

    • Environment: You see or hear a phone number (e.g., 607607).

    • Sensory Input: The physical act of seeing or hearing the number enters your sensory register.

    • Attention: Only if you pay attention does the information move from the sensory register into the short-term memory.

    • Short-Term Memory (STM): The phone number temporarily resides here.

    • Rehearsal: Repeated rounds of repetition (the blue arrow in diagrams) are necessary for consolidation.

    • Long-Term Memory (LTM): If rehearsal is successful, the information is consolidated into long-term memory.

    • Retrieval: To recall the phone number, it is retrieved from LTM back into STM, allowing you to verbalize it.

Properties of Memory Stores

  • Sensory Register:

    • Duration: Very, very brief amount of time (e.g., remembering a phone number you just heard for a split second).

    • Capacity: Enormous; captures all sensory input (everything you see, hear) before attention is applied. You don't remember every small detail from your environment.

  • Short-Term Memory (STM):

    • Duration: Approximately 10−2010-20 seconds without rehearsal. With rehearsal, it can stay significantly longer.

    • Capacity: Limited to about 4 ext{ } oldsymbol{ ext{ extpm} ext{ }} 1 chunks of information. Chunking (grouping information, like phone numbers into 3−3−43-3-4 digits) can effectively increase capacity.

  • Long-Term Memory (LTM):

    • Duration: "Permanent?" Technically, for the entire duration of your life, but forgetting can occur due to interference or retrieval failure.

    • Capacity: "Infinite." From current understanding, its capacity is essentially limitless.

Mechanisms of Forgetting

Forgetting can occur at all three stages of the multi-store model due to various reasons.

Ineffective Encoding (Pseudo-Forgetting)

  • Definition: This is when information never properly makes it into memory due to a lack of attention or proper storage by the brain.

  • Location: Happens at or before the sensory register.

  • Nature: Not technically