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Dual-Store Theory of Memory
- Early cognitive psychologists believed in one memory store.
- William James (1890) proposed two separate stores:
  - Primary Memory (short-term memory, STM) – items in conscious awareness.
  - Secondary Memory (long-term memory, LTM) – items stored for longer periods, not currently conscious.
Definitions:
- Short-term memory (STM):
  - Temporary storage for information receiving attention.
  - Limited duration and capacity.
- Long-term memory (LTM):
  - Permanent storage for future retrieval.
  - Vast capacity, can last a lifetime.
Atkinson and Shiffrin Model (1968): STM and LTM are distinct stores; introduced a third store for sensory information.

STM Duration:
- Amnesic patients provide insights into STM duration. e.g., patient CW retains info for about 7 seconds.
- Brown-Peterson Task: participants retain test items interrupted by a distraction. Results indicate rapid forgetting.
- Most items forgotten within 5-10 seconds when rehearsal is prevented.
STM Capacity:
- Typical measure: immediate memory span test (recall of digits or words).
- Average span is about 7 items (Miller, 1956) with variations (5-9 range).
- Digit Span: max digits correctly recalled immediately.
  - Difference between immediate and delayed recall, highlighting STM's limited capacity.

Working Memory Definition: Active processing of information, not just a storage space. More dynamic than traditional STM.
Baddeley and Hitch (1974) found:
- Two short-term stores replace the single STM store concept.
- Short-term tasks effect does not occur with different sensory modalities (visual vs. auditory).
Components of Working Memory:
- Phonological Loop: stores auditory info.
- Visuo-spatial Sketchpad: stores visual info.
- Central Executive: manages activities of the two stores, controls attention and processing.

Function: Holds verbal and auditory information. Critical for tasks requiring short-term retention of auditory input.
Evidence:
- Performance of a verbal task is disrupted by simultaneous performing another verbal task (articulatory suppression).
- Distinction between phonological store and articulatory control process (inner speech).
Word-Length Effect:
- Better recall for shorter words; span limited by how long it takes to say items.
Applications: Important for language acquisition, as deficits in the phonological loop correlate with language learning difficulties.

Capacity Measurement: Similar to digit span but involves visual tasks (e.g., Corsi Blocks test).
Evidence for Existence:
- Performance in visual tasks severely disrupted by adding another visual task but unaffected by auditory tasks.
Sub-components:
- Visual Cache: stores visual details.
- Inner Scribe: deals with spatial information, assists movement control.

Role: Oversees cognitive processes, controls the phonological loop and visuo-spatial sketchpad.
Functions Identified (Miyake et al., 2000):
- Inhibition: suppressing dominant responses.
- Shifting: switching attention among tasks.
- Updating: monitoring new input and stored data.

Episodic Buffer: New component proposed to integrate information from different modalities, linking WM and LTM.
Neuroimaging Evidence: shows distinct brain areas are activated during different WM tasks, supporting the multi-component model.
Individual Differences: Variations in WM performance correlate with real-life outcomes (e.g., academic success, cognitive abilities).
Recent research continues to refine and challenge existing models of WM.