Short term and Working Memory- Lecture 4 Flashcards
Organic amnesia & STM
Suggests there is a form of memory of limited duration and capacity- short term memory
Peterson and Peterson (1969)
Duration of STM
18-30s- trigram memorability declined with time past 30 s
Miller (1956)
Capacity of STM
7+-2 items
Visual STM span
Corsi (1972)
Corsi blocks test- have to memorise the order that someone taps different blocks in a sequence- numb
CHUNKING- STM storage
- Personal semantics
- Prosodic preferences-grouping into 3s
- Phonological plausibility- pronounceable?
- Expertise (e.g. language, familiar with something that is similar to words)
STM capacity revisited
Cowan (2010)
range of 3-5 chunks with verbal materials in a variety of tasks
Miller (1956) digit span- criticism
Researchers have suggested that in the digit span of Miller, people may rehearse (covertly) and combine individual items into chunks.
Storage capacity of visuospatial STM revisited
Accuracy of scores for different array sizes shows a big drop off when array size exceeds 4 items- we store integrated objects (e.g. purple square in right corner)
How do we integrate the elements?
The multi-store model of memory
Atkinson & Shiffrin (1968)
A serial sequential model- transferring info from one box to another
Main function of store is to rehearse info until it is retained in LTM
Completely wrong?- disproven year after…yet still prominent
Warrington & Shallice (1969)
Neuropsychological evidence:
- Patient KF- impaired STM- limited digit span, but normal LTM
- No transfer of information
- Parallel inputs from sensory stores go to both STM and LTM
- Doesn’t need to be subjected to rehearsal to reach LTM
Is STM a unitary store?
Patient KF an others show deficits in verbal STM but not in visuospatial STM
Other patients show the reverse impairment
Multi component model of working memory
Baddeley and Hitch (1974) proposed that STM is composed of three, limited capacity stores:
central executive
phonological loop
visuospatial sketchpad
Phonological loop (inner ear)
Model of verbal STM- stores verbal info for a brief period
Articulatory control system-
-Rehearses sub-vocally the contents of the store to prevent forgetting.
-Converts written language into sound (phonological code) so that it can enter and be maintained in the phonological store.
Peterson & Peterson (1959) Phonological loop rehearsal
The contents of the store are rehearsed to be remembered
Evidence for phonological loop
Phonological code and phonological similarity effect
When words sound similar it is harder to remember them
Easier when not phonologically similar
Evidence for PL capacity
Based on number of sounds we can store
Length of words affects digit span- because there are more sounds in
Increasing word length decreases number of items can hold in PL as take longer to rehearse
Different processing mechanisms for written and spoken words
Ppts presented with spoken and written words and later asked to recall
Given articulatory suppression task- disabled the articulatory control process- favoured remembering written words
Baddeley, Papagno & Vallar, (1988)
Why do we need the phonological loop?
PV case study could learn word pairs in native Italian, but could not learn Russian word pairs- While word pair learning relied on existing semantic links (limited need for phonological coding), foreign word learning relied on phonological processing
Evidence for separate stores
Quinn and McConnell (1996)-
-Using visual or verbal interference
dealing with two different substances- one for visual info and one for verbal
Logie (1995) different stores within VSSP
Visual and spatial info depend on different stores:
- Visual cache: visual info e.g. object shapes, patterns and colours
- Inner Scribe: spacial info e.g. object location and movement & also rehearses contents of visual cache
Evidence for 2 stores for visual and spatial info
Klauer & Zhao (2004):
- Given a visual (remember ideogram) or spatial (remember location of a dot) memory task
- Interference tasks- visual or spatial or control
- Results showed that when type of interference task congruent to memory task, recall was worse
Episodic Buffer
- Newest component
- takes elements from both phonological store and visuospatial sketch pad
- Where we store integrated forms of objects
- Capacity of 4 chunks
Central Executive
Attentional Control system
Attentional control system:
- Automatic control system- for decision making in complex but habitual situation
- Supervisory attentional system- decision making in novel situations
CE main operations
The CE:
- Receives input from the subsystems
- selects and evaluates streams of information
- overrides responses
- switches between tasks
- constantly monitors outcomes
Dual task performance tests
Used to explore the CE- as required to switch between tasks and to inhibit previous responses
Dysexecutive syndrome
Damage to the frontal lobes & also in some Alzheimers patients
Issues with executive functioning
Alternative state theories of WM
Cowan’s (1999) Embedded processes model
- Working memory does not consist of separate temporary stores (buffers) but operates within LTM.
- Central executive which directs attention on specific features within LTM.
- Attentional focus may be triggered by external or internal events
- Depending on stimuli, goals and tasks, different features in different states of activation. Attention can focus to all activated items in turn
Brain areas involved in Working memory functions
> Frontal lobes: executive functioning
Parietal & occipital cortices: processing and maintenance of actual stimuli (location, object, or speed specific)
-A hierarchy emerges: The PFC sends signals to posterior cortices (top-down signals) to enforce the rules and maintain goals
