Notes on Memory

Memory

Introduction to Memory

  • Memory defined as maintaining information over time.
  • Three stages in learning and memory process (Melton, 1963):
    • Encoding: Initial learning of information.
    • Storage: Maintaining information over time.
    • Retrieval: Accessing information when needed.
  • Stages affect each other; all are interconnected.

Encoding

  • Initial registration of information essential for memory.
  • Must be encoded for successful recall later.
  • Memory traces, or engrams, represent neural imprints of experiences but are not perfect recordings of experiences.
  • Remembering is reconstructive, not reproductive:
    • Memory involves reconstructing past experiences aided by current beliefs and memory traces.

Structure of Memory

  • Information enters cognitive system through sensory organs.
  • The structure of memory is debated:
    • Some argue for multiple stores (different capacities/durations).
    • Others argue for a single store with varying processing types.
  • Atkinson and Shiffrin’s Model (1968):
    • Three Stores:
    • Sensory Store: Initial, brief storage; holds sensory impressions.
    • Short-Term Store (STM): Temporary storage for ongoing information.
    • Long-Term Store (LTM): Consolidated, more permanent information.

Atkinson & Shiffrin Modal Model of Memory

  • Information processing approach where data transitions from sensory to short term to long-term memory.
  • Control Processes:
    • Strategies used to transfer information between stores
    • Examples:
    • Rehearsal: Repetition of information to maintain it in STM.
    • Coding: Altering the form of information (e.g. acronyms).
    • Imaging: Visualizing information for better recall.
  • Fixed memory structures versus variable control processes.

Evidence Supporting Different Memory Systems

  • Physiological data from animal studies:
    • Learning disrupted by shocks affecting STM to LTM transfer.
  • Amnesia patients exhibit patterns aligning with the model (best recall of older memories, loss of recent ones).
  • Serial Position Effect: Items at the beginning (primacy effect) and the end (recency effect) of a list are remembered better than those in the middle.
Serial Position Curve
  • Explains the U-shaped curve of recall performance based on item position in a list:
    • Primacy Effect: Better recall of first items due to rehearsal and LTM transfer.
    • Recency Effect: Better recall of last items still in STM.
    • Poor recall of middle items due to lack of rehearsal.
Evidence of Memory Systems
  • Glanzer & Cunitz (1966):
    • Manipulated presentation speeds influence primacy effect but not recency effect.
  • Distractor tasks reduce recency effect but not primacy effect.

Sensory Memory

  • First memory store, maintaining raw information briefly after stimulus cessation.
  • Iconic Memory: Visual sensory impressions retained briefly (around 250 milliseconds).
  • Echoic Memory: Brief auditory sensory memory.
  • Partial-Report Technique (Sperling, 1960): Shows sensory stores hold more information than whole reports indicate.

Short-Term Memory (STM)

  • Functions as a holding and recycling buffer for current information.
  • Limited capacity: 7 +/- 2 items (Miller, 1956).
  • Chunking: Storing items as groups enhances capacity.
  • Coding: Primarily acoustic; visual information often represented as sound (Conrad, 1964).
  • Duration: Lasts about 20-30 seconds (Brown, 1958; Peterson & Peterson, 1959).
    • Lost via decay or interference.
Mechanisms of Forgetting in STM
  • Decay: Lost due to the passage of time without rehearsal.
  • Interference: Difficulty recalling target items due to the presence of other information.
    • Proactive Interference: Previous memories inhibit new learning.
    • Retroactive Interference: New information disrupts older memories.
Research Findings on Interference
  • Waugh & Norman (1965): Found interference more impactful than decay, emphasizing proactive interference.
Release from Proactive Interference
  • Changing the semantic category of items can alleviate proactive interference. (Wickens et al., 1963).

Retrieval of Information from STM

  • Search Methods:
    • Serial vs. Parallel Searches.
    • Self-Terminating vs. Exhaustive Searches:
    • Self-terminating: Stops searching after finding the target.
    • Exhaustive: Searches through entire set regardless of finding the target.
  • Sternberg's Study (1966): Showed exhaustive search processes in STM retrieval.

Working Memory

  • Baddeley & Hitch (1974): Revised the STM model to include working memory.
  • Components of Working Memory:
    • Phonological Loop: Manages verbal material through subvocal rehearsal.
    • Visuospatial Sketchpad: Maintains visual and spatial information.
    • Central Executive: Controls attention and integrates information across systems.
    • Episodic Buffer (Baddeley, 2000): Integrates material from various sources.

Conclusion

  • Working memory represents a dynamic system that elaborates on STM functions.
  • Memory is complex, integrating information across different modalities and processes.