Short term memory (the first model)
As the individual receives incoming stimuli from their sensory registers, any stimuli that the individual attends to will then be moved on to short term memory, which has a longer life span than the sensory registers. There are three key traits to short term memory:
1. We can typically remember 7+/-2 chunks of information at a time. (Miller, 1959)
2. Short term memory has a limited duration. Typically about 15-30 seconds without distraction or rehearsal.
3. Short term memory is typically acoustic. Even visual information may be translated into words or phrases in order to be retained.
However, since Miller's research in 1959, research has been expanded on the short term memory model to Atkinson and Shriffin (1968)'s multi-store model of memory, and then to Baddeley and Hitch (1974)'s working memory model.
This portion of the OLC discuss various aspects of the different models.
According to Miller, (1959), our short term memory (or working memory) has a capacity for approximately 7 +/- 2 objects for adults. Further research by Miller has found that each object is best thought of as a chunk of information, which is the largest unit of meaningful information an individual can recognize. For example, The letters 'ba' are made up of two letters, but can be grouped together into a chunk, and remembered as one group.
Although this rule has served as a good rule of thumb for many years, more recent research has determined that this length depends on a host of other factors. The types of objects for instance, would affect the number of chunks that can be recalled by people. (typical number for digits is 7, 6 for letters, and around 5 for words). Storage capacity also depends on the size of the chunks, and on the lexical status of the chunk. For example, a chunk consisting of a word would be easier to remember if the individual understands the meaning of the word.
Miller's law, and the idea that short term memory acts as a series of stores, is the main proposal behind Atkinson and Shriffin's (1968) multi store model of short term memory.
How well does your working memory compare to others? Try this test and find out: https://www.psychologistworld.com/memory/test2.php
Working Memory Model (Baddeley and Hitch, 1974)
Baddeley and Hitch (1974) expanded on of short term memory. This new model, called working memory, expanded upon the existing model by dividing short term memory into 3 components: The Visuo-Spatial Scratch pad (VSS), the Central Executive, and the Phonological loop (PL). Later on in 2000, Baddeley adds a 4th component, the episodic buffer. (Baddeley, 2000)
The Central executive
This component of the working memory model serves as controller of the VSS and the PL. The central executive directs the individuals attentions to different stimuli and monitors the activities of the VSS and PL (which act like slave systems). The central executive also relates with long term memory to recall information that aids in decision making.
For instance, while you are driving your car, most of your concentration would be targeted towards the road for traffic. When your passenger asks you a question, your central executive may decide to shift some of the attention from the road to your passenger, in order to address their comments.
The Phonological loop
The phonological loop a process that describes how auditory information is processed and stored in working memory. When the auditory stimuli enters working memory, it enters the phonological store and remains for 1-2 seconds. This information can then be processed by the central executive.
To retain the auditory, or speech information for more than the normal 1-2 seconds, the individual can rehearse the information repeatedly, which allows the information to enter the phonological store again. This is best illustrated in how people tend to remember phone numbers by repeating them over and over.
The visual spatial sketchpad
The visual spatial sketchpad deals with spatial and visual information presented to working memory either from sensory registers, or from long term memory. The information stored on the sketchpad allows the central executive to make decisions based on visual information. It has been theorized that the visual spatial sketchpad allows us to maneuver around our surroundings by interpreting visual information constantly and relating it to images stored in our long term memory (Baddeley, 1997)
The episodic buffer
The episodic buffer was added by Baddeley in 2000 to explain the results of experiments performed since the initial creation of the model. The episodic buffer serves as a 4th component that combines visual, spatial, verbal, and temporal sequencing information. The episodic buffer helps explain the observations that some patients who suffer from amnesia was still capable of good short term recall of stories, which required much more than a functioning phonological loop.
Discussion question: Now that you have read about Baddeley's model of working memory, what classroom strategies can you come up with that will aid a student retain more information in the long run? Discuss in the Connect forum.