By Mr Daniel Hansson
Important definitions
 Encoding: When an experience is converted into a
memory construct
 Storage: When a memory is stored over time
 Retrieval: Recall of memories
Atkinson-Shiffrin (1968)
Sensory store
 A temporary buffer store holding information from the
environment very briefly in an unprocessed state
 Is modality specific, i.e. information is held in the
form in which it is received (visual, auditory, tactile or
olfactory) E.g. iconic (visual) and echoic (auditory).
 Information not attended to is forgotten
 Sperling (1960) has demonstrated that the capacity of
the sensory store is at least 12 items, but it is probably
vast
Short term memory (STM)
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What we are attending to, our awareness
Has limited capacity: Only about 7 items or
chunks can be stored at a time. (Miller, 1956)
Has limited duration: Storage is very fragile and
information can be lost with distraction
(displacement) or passage of time (decay), between
18-20 seconds) (Peterson & Peterson, 1959)
Encoding is primarily acoustic.
Long term memory (LTM)
 Has theoretically unlimited capacity
 Encodes memories by meaning
 Information that is rehearsed in short term store may
be stored in long term store
 Information is stored a longer time
 Forgetting in long term memory can occur through
interference of memories, decay, or repression
 Cues, the same emotional states or environments
where a memory was encoded can aid recall
Supporting research for a short
term and long term store
 Miller (1956) has demonstrated that the capacity of the short
term store is 7+-2 information units.
 Glanzer and Cunitz (1966) have demonstrated that there are
separate memory stores, because of primacy and recency
effects (the first and last items of memory lists are more likely to
be recalled) This is because the first items are rehearsed and
enters long term store and the last items are still in STM.
 Case studies, such as the one of HM (Milner, 1950) demonstrates
that there are separate memory stores, because HM had an
almost intact long term memory but was not able to learn new
things (STM).
 Peterson & Peterson (1959) have demonstrated that the duration
of STM is about 20 seconds.
Strengths of the model
 Supporting research
 The experimental research is well controlled
 Brain research supports that there are different
localizations of memory mechanisms in the brain
 The model can account for primacy and recency effects
 The model has generated a lot of research into
memory
Weaknesses of the model
 The model is criticized of being to linear (research suggests that the memory stores work
more unitary. For instance, LTM may influence what we attend to and what we store in
STM
 Cowan (2000) has suggested that the number of items to be stored in STM is more likely
to be 4
 There are other ways than just rehearsal and attention to memorize, such as through
meaning (e.g. schemas) and emotion (e.g. flashbulb memories)
 Ecological validity problem of the supporting experimental research (this is not the usual
way we memorize, unless we encode phone numbers, shopping lists or vocabulary)
 A possible cultural bias of the model. Studies (e.g. Cole and Scribner, 1974) show that
children without schooling do not show primacy effect (do not rehearse information)
 Baddeley and Hitch (1974) have demonstrated that STM is not just a unitary store and
consists of several components (e.g. visuospatial sketchpad, phonological loop, central
executive)
 Research suggests that we do not have one, unified LTM, but different types of LTM, such
as episodic (memory of events) and semantic LTM (general knowledge) and procedural
memory (memories of skills)