Memory & Learning

Memory Over Different Time-scales

• Two kinds of Knowledge

  • Hard-wired (comes naturally, ex: breathing, eyes movement)

  • Learned (memories and gained through experiences)

  • Squire: learning is the process of accquiring new info and memory refers to the persistence of learning in a state that can be revealed at a later time

  • Function of memory

    • Fundamental task of memory

    • It is used to increase our ability to function in the present & future based on our past experiences.

• Varieties of Memory

  • Time Scale: long-term/ short-term/ sensory memory

• Sensory Memory

  • Large amount of info for the shortest period of time

    • Quickly overwritten by new incoming info

  • Short-Term Memory (STM)

    • Working memory

    • A limited capacity store, used for maintaining an active representation of info for a brief amount of time

    • Size of STM

      • Digit-span task: repeat a string of digits (normal span: 7 digits)

      • Spatial-span task: remember locations of flashing boxes in exact order (normal span: 6 locations)

    • The Modal Model

      • Hypothesis: STM is a gateway to LTM

Working Memory (Rethinking STM)

• The Braddeley-Hitch Model

  • Working Memory: dynamic memory proess in which the recent information is worked on

    • contrast with the passive nature of a simple information store

  • 3 important characteristics (different from modal model)

    • Short-term storage is not a gateway to LTM

    • Proposes central executive that manipulates what goes in and out of STM

    • Two memory buffers:

      • Phonological Loop

        • Hypothesized mechanism for encoding info acoustically in working memory

      • Visuospatial Scratchpad

        • Info encoded in either purely visual or visuospatial forms

    • Central Executive: command and control center that coordinates interaction between the two system.

      • Dual Task: Remember two things in a row

        • Same task version

        • Different task version

Different Types of LTM

• Stages of Memory

  • Encoding: acquisition of memory

    • Consists of many features distributed across different neural systems (sensory, conceptualm emotional)

    • Successful encoding requires

      • Feature Binding: features from a single memory must be linked into a feature pattern to ensure a complete memory

      • Pattern Separation: features from different memories must be distinguished to avoid confusion of similar memories

  • Storage: retention of memory traces over time

  • Retrieval: accessing stored memory traces

    • Retrieval Cue

    • Pattern Completion

    • Pattern Evaluation

• Varieties of LTM

  • Case study of Henry Molaison 

    • Bilateral medial temporal lobectomy

    • Normal STM

    • Severly impaired LTM

      • Couldn't form new memories (anterograde) + some temprarily graded retrograde

  • Declarative Memory

    • Declarative Knowledge: a conscious knowledge of facts and events

    • Episodic: Knowledge of specific personal experiences, their contents and time place

    • Semantic: world and word knowledge

  • Non-declarative memory

    • Procedural memory: knowledge of processes (motor, perceptual, cognitive)

  • Implicit Vs Explicit Memory

    • Implicit Memory (Non-declarative): knowledge that can be retrieved without conscious recollection.

    • Explicit Memory (Declarative): knowledge that can be retrieved only with conscious recollection