Memory Codes
• Auditory, visual, tactile, gustatory,
olfactory, semantic, verbal (words)
Sensory vs. STM
• Sensory memory
– ICON – visual format or visual code
– ECHO – acoustic code
– Generally, code is the same as the sense
– E.g., Touch sensory memory  tacticle
Sensory vs. STM
• What is the code in STM?
• Example study (Conrad, 1964)
– Used the span task with letters (presented
visually)
– Very accurate, but occasionally make
mistakes  he studied the mistakes (when
people remember the wrong letter)
Confusion mistakes (confusions)
• When you remember the wrong letter,
– The wrong letter could look like the letter you
saw (visual confusion)
• E.g., saw L  I
– The wrong letter could sound like the letter
you saw (acoustic confusion)
• E.g., saw P  T
Results
• The vast majority of the mistakes were
acoustic confusions
• Conclusion  STM involves acoustic
coding
• More generally, acoustic coding is
common in short-term memory
Atkinson-Shiffrin model (1968)
• Model of different memories, their codes,
and the processes that access the
memories
• 3 kinds of memory:
– Sensory memory
– Short-term memory
– Long-term memory
Flow of memory
• Stimulus from environment
•  stimulus represented in sensory
memory (small capacity, extremely brief
duration, code is related to the sense
[sensory modality])
•  stimulus represented in STM (limited
capacity, duration up to about 30 seconds,
primarily acoustic code)
Flow (cont.)
•  stimulus represented in LTM (infinite
capacity [unlimited], infinite duration,
variety of codes)
• Aka, the “modal model”
• See p. 83 for the diagram of this
information processing model
Another model of short-term
memory
• Emphasizes the “working” aspect of
memory
• Called the Working Memory Model
(Baddeley, 1986)
• Three components to short-term memory:
phonological loop, visuospatial sketchpad,
central executive
Phonological loop
• Hold small amount of information in terms
of the way it sounds (acoustic coding)
– Phonological sounds come from your
language
– Acoustic = any sounds
• Can hold about 2 seconds worth of
phonological information at a time (like an
audiotape) [capacity]
Visuospatial sketchpad
• Like a drawing tablet, with only so many
things drawn at a time (limited capacity,
visual code)
• Holds not only the visual information (what
things look like), but also how they are
arranged (spatial information)
Central executive
• Monitors, keeps track of, arranges
information, etc. within the phonological
loop and the visuospatial sketchpad
• E.g., central executive involved in moving
information from phonological loop to LTM
• Also, converts information from one code
to another
Diagram of WM Model
Phonological Loop
Central
Executive
VSS
Current state of A-S & WM Model
• A-S: still most commonly accepted model
of memory, including outside of cognitive
psychology, and out into general public
• WM: used outside of cognitive psychology,
especially in neuropsychology or
neuroscience