Types of memory and models of memory

Alyssa Alcorn
Henry S. Thompson
14 October 2010
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1. Introduction to short-term memory

Short-term memory (abbreviated as STM) is responsible for storing small amounts of material over short periods of time

STM has often been tested with verbal or visual information,

Short-term memory and working memory have different functions and are not interchangeable terms

2. The magical number seven, plus or minus two

Classic research by George Miller (1956) described the apparent limits of short-term memory span

Most people appear able to have a memory span of 5-9 items (average of 7)

3. Memory span continued

Short-term memory span can be ‘stretched’ by meaningfully grouping or chunking information

Memory span for words in a sentence is significantly longer than for unrelated, context-less words

4. Introduction to working memory

Working memory (abbreviated to WM) is a ‘mental workspace’

This concept that assumes some part of the memory system does the following:

Different theories and models of memory have more or less complex versions of this concept

An example of working memory: adding two multi-digit numerals in your head

Short term memory is one component of the larger working memory system

5. What about long-term memory?

Long-term memory (abbreviated LTM) is a system which stores information over long periods of time

A “long period of time” can be a few minutes or an entire lifetime

LTM can be divided into explicit (declarative) memory and implicit (non-declarative) memory

Explicit memory includes

Implicit memory includes information that is retrieved by performance,

6. What good is a model?

Models can test theories of memory (or other phenomena)

How good is a model?

Moreover, creating a model forces precision and computational completeness for a theory

This class will focus on the Baddeley-Hitch model of memory.

This is not the only model of memory, but a good place to start

7. The Baddeley-Hitch model of memory

This Baddeley-Hitch model(B-H) is also more informatively called the multicomponent theory

Originally proposed in 1974

Involves the following pieces:

  1. A phonological loop for verbal and auditory information
  2. A visuo-spatial sketchpad for visual and spatial information
  3. A central executive as an “attentional controller”
  4. A multi-dimensional episodic buffer and episodic LTM
    • The episodic buffer is a more recent addition to the B-H model, about a decade ago
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Diagram from Baddeley (2003), in refs on last slide

8. The phonological loop

Component of the B-H model which temporarily stores speech or verbally encodable information

The phonological loop is composed of two subcomponents:

Information goes into this store if

9. The phonological loop, cont'd

The phonological loop accounts for the phonological similarity effect

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The word length effect

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10. The visuo-spatial sketchpad

This store is responsible for image-based information, and is also subject to memory span limits.

Appears to consist of two subsystems which work closely together to hold and manipulate information

One illustration of a span limit on the sketchpad is visual pattern span (Della Sala et al. 1999)

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11. A new addition: the episodic buffer

The original B-H model struggled to explain interactions between working and long-term memory.

The episodic buffer has been suggested as an additional component to link memory subsystems with perception and LTM input/output

Binding is the process of linking individual object features into complete objects

12. Putting it all together: The central executive

These subsystems for different types of information do not operate autonomously

The central executive is like the air-traffic control tower of the memory system

The central executive is a very important concept in cognition

We will return to this when studying attention

13. Baddeley-Hitch model recap

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Phonological loop for speech or any information that can be verbally encoded and rehearsed

Visuo-spatial sketchpad for image information, objects and features, spatial locations/relationships

Central executive for selecting and controlling information flow

Episodic buffer for additional storage and binding information

Long-term memory for prolonged storage of declarative and non-declarative information

14. References

Course texts

Optional readings

Other resources, available through the library or Google Scholar