Working Memory (4)

Short-Term Memory/Working Memory

  • Atkinson & Shiffrin model of memory: Comprises three primary components: sensory memory, short-term memory (STM), and long-term memory (LTM).

  • Sensory memory: Briefly retains sensory information from the environment.

  • Short-term memory (STM): Temporarily holds information for processing.

  • Long-term memory (LTM): Stores information over prolonged periods.

  • The STM/LTM division: Distinguishes between temporary and permanent storage systems.

  • Early studies of coding in STM: Investigates how information is represented and recalled.

  • Baddeley’s Working Memory view: Expands on STM by introducing a dynamic system for manipulating information.

Atkinson & Shiffrin: Sensory Memory

  • Characteristics of sensory memory:

    • Lasts very briefly (milliseconds).

    • Closely tied to the original sensory input modality (e.g., visual information remains visual).

  • Form of Representation: Sensory representation aligns with the form of the external stimulus (auditory stays auditory, visual stays visual).

  • Forgetting in sensory memory: Information decays rapidly; e.g., iconic memory (visual) lasts ~300 ms.

  • Processing information: Information not lost is transferred to STM for further processing.

Atkinson & Shiffrin: Short-Term Memory

  • Characteristics of STM: Holds information temporarily for further processing and use.

  • Form of Representation: Information is primarily stored acoustically; primarily through sound.

  • Forgetting in STM: Information decays within seconds; rehearsal can extend this duration.

  • Capacity:

    • Defined by George Miller (1956) as the ability to remember approximately 7 ± 2 items (chunking can enhance memory capacity).

  • Where information goes: Rehearsed information progresses from STM to LTM.

Atkinson & Shiffrin: Long Term Memory

  • Form of Representation: In LTM, information is primarily stored semantically, meaning by context and understanding.

  • Forgetting in LTM: Little to no forgetting; information is typically stable and retrievable.

  • Capacity of LTM: Considered to be very large, possibly unlimited.

  • Retrieval: Information stored in LTM can be brought back into STM for application.

Summary of the Atkinson & Shiffrin Model

  • Structural Features: The model comprises three core components: sensory memory, STM, and LTM.

  • Control Processes: Refers to voluntary strategies for managing information, such as maintenance rehearsal to keep information active.

The STM/LTM Division

  • Introspection: Reflects on inner thoughts regarding memory processes.

  • William James’s concepts: Differentiates between primary (immediate) and secondary (stored) memory.

  • Evidence: Supported by various studies showing the distinction in memory functionalities.

Evidence from Rundus (1971)

  • Free recall task: Participants hear a list of words and recall them in any order.

  • Primacy and recency effects:

    • Early recalled words are likely stored in LTM.

    • Later recalled words remain in STM.

    • Words in the middle are more likely to be forgotten.

Evidence from Patient Data

  • Patient H.M.:

    • Demonstrated intact STM but impaired LTM recall post-surgery.

    • Able to remember events before surgery but unable to form new memories.

  • Korsakoff syndrome: Similar memory impairment, supporting the STM/LTM division.

Early Studies of Coding in STM

  • Speech-based (verbal) code:

    • Coding is primarily based on sound, evidenced by phonological/acoustic confusability effects.

    • Conrad and Hull (1964) showed that memory for similar-sounding items is poorer.

    • Example findings included errors with acoustically similar letters.

Conrad’s (1964) Study Dissection

  • Error types:

    • Analyzed errors in recalling similar sounding items.

    • Showed patterns of confusion among acoustically similar stimuli.

Visual Coding in STM

  • Visual coding: Can be effective when verbal coding is limited (Brandimonte et al., 1992).

  • Differences among populations: Variances in memory retention observed between hearing and deaf individuals due to phonological vs. cherological factors.

Semantic Coding in STM

  • Release from proactive interference:

    • Proactive interference: Difficulty in learning new information due to prior learning.

    • Changing semantic categories can improve recall, demonstrating the flexibility of LTM and STM.

Baddeley’s Working Memory View

  • Working Memory: A system for temporarily holding and manipulating information.

  • Components:

    • Phonological loop: Processes sound-based data (left hemisphere).

    • Visuospatial sketchpad: Manages visual and spatial information (right hemisphere).

    • Central executive: Directs attention and resource allocation (frontal lobe).

    • Episodic buffer: Integrates and stores information briefly, working between systems.