Working Memory and Cognitive Control Lecture Notes

Introduction to Working Memory

• Definition: A system for holding and manipulating information over short periods of time.
• More than storage: Includes active processes such as focusing attention and controlling information.
• Importance: Central to conscious thought and behavior.

Short-Term Memory (STM)

• Duration: Approximately 20-30 seconds.
• Capacity: Typically around 7 items (plus or minus 2).

Demonstration of STM Capacity

• Example: Remembering phone numbers by rehearsing them in your head.
• Capacity Experiment: Participants recall around 7 letters in a sequence.

Chunking

• Definition: Grouping information into meaningful units (chunks) to increase STM capacity.
• Example: Acronyms like FBI, CIA group into single chunks rather than individual letters.
• Pre-existing knowledge: Long-term knowledge helps in chunking information.

Rehearsal in STM

• Importance: Allows for holding information longer by actively refreshing it.
• Interference: Prevents rehearsal by introducing tasks like counting backward.
• Experiment: Participants forget most information after 15-18 seconds of interference.

Mechanisms of STM Loss

• Decay: Information fades over time.
• Interference: New or old information disrupts current memory.
  • Proactive Interference: Old information interferes with new information.
  • Retroactive Interference: New information interferes with old information.
• Experiment: Studies demonstrate interference is a more robust mechanism than decay.

Storage Models of Memory

• Atkinson-Shiffrin Model: Sensory memory, short-term store, long-term store.
  • Sensory Memory: Brief storage of sensory information; lasts a few seconds.
  • Short-Term Store: Limited capacity (about 7 items), duration up to a minute.
  • Long-Term Store: Large capacity, duration can be a lifetime.

Sensory Memory

• Experiment: Partial report technique suggests large capacity but brief duration.

Working Memory Model (Baddeley and Hitch)

• Components:
  • Central Executive: Controls attention, sets goals, monitors errors.
  • Visuospatial Sketchpad: Stores visual and spatial information.
  • Phonological Loop: Stores speech and sound-based information.
  • Episodic Buffer: Integrates information from various sources (e.g., visual, phonological).
• Interference Experiments: Dual task paradigms show interference when similar types of information are processed together.

Central Executive Functions

• Controlled updating of STM: Tasks like the n-back task and self-ordered search.
• Setting goals and planning: Tested with the Tower of Hanoi task.
• Task switching: Assessed with the Wisconsin Card Sorting Test.
• Selective attention and inhibition: Evaluated using the Stroop task.

Key Takeaways

• STM is limited in both capacity and duration.
• Chunking and rehearsal can improve STM performance.
• Interference is a primary mechanism of memory loss in STM.
• Working memory is a dynamic system involving multiple components.
• The central executive plays a crucial role in managing cognitive tasks.

Practical Implications

• Understanding STM and working memory helps in developing strategies for learning and memory improvement.
• Insights into working memory function can inform clinical practices, especially in managing conditions affecting cognitive control and memory.