Lecture 9 - the remembering brain P2 Flashcards
short term memory
memory for active information
long term memory
stored information that isn’t presently/consciously accessible
working memory
a system for the temporary storage and manipulation of information
- the active manipulation of info within the STM store to serve higher cognitive functions
Baddeleys (2000) model of working memory
seperate STM stores and an executive system for manipulating and controlling info within the stores
- visuospatial sketchpad
- episodic buffer
- phonological loop
where is the phonological store in the brain
- lies posteriorly
- in parietal lobes
Smith et al 1996 - PET study on Model of Working Memory
- tested Ps on short-term retnetion fo either letters (verbal STM) or location of markers (visual STM)
- found distinct brain regions are active in two tasks
- verbal STM - left hemisphere
- visuospatial STM - right hemisphere
what did Miller (1956) suggest the capacity of the STM was:
7 +/- 2 - meaningful ‘chunks’ of information
what does chunking rely on
- relies on LTM and on LTM and STM interactions
what did Cowan 2001 suggest the capacity of the STM is
lower - around 4
why is the span of the STM capacity not related to the meaningfulness of chunks? (BADDELEY 1996)
- span length lower for polysyllabic words (eg. skeleton)
- span length lower for phonologically similar words (map, cat, cap etc.)
what does the capacity of the STM depend on according to Baddeley
- opportunity to rehearse the material - ARTICULATORY SUPRESSION
Span tasks rely on what two components according to Baddeley?
- phonological store component (verbal STM)
2. and a rehearsal mechanism
Paulesu et al 1993 - PET study on the separation of the phonological loop
PS performed task either:
a. STM for letters (both store and rehearsal components)
b. rhyming judgements (rehearsal only)
- phonological store > LEFT SUPRAMARGINAL GYRUS
- rehearsal system > BROCAS
two models of Visuospatial STM
SLOT MODEL: a small number of memory ‘slots’ each capable of storing a single visual object
RESOURCE MODEL: no upper limit on no. of items stored - BUT the more items held in memory - the less precisely they can be recalled.
Luck and Vogel (1997) on the slot model
- brief displays of arrays (incl. coloured squares and oriented coloured lines)
- PS could retain information about only FOUR colours or orientations in visual WM at one time.
BUT they could retain info about colour AND orientation of four objects
so - visual STM capacity understood in terms of integrated objects NOT individual features.
Bays, Catalao and Hussain (2009) and the resource model
- Ps exposed to arrays which contained 1-6 coloured squares
- they were presented with test array with a prop to recall one of the squares colours.
- precision of recall decreased with increase of item on the array
Ranganath et al 2004 - neural correlates of visuospatial STM (procedure)
- delayed matching sample: PS shown Face/place and asked to keep it in mind - then test stimulus shown
- in delayed paired associates - PS had previously learned to pair particular face and place images together
ignore
okay
what does the delayed-response task measure
this measures working memory
delayed response task in monkey
monkey must continue t retain the location of the unseen food during delay period (WM)
- lesions to prefrontal cortex impacts this ability
- but is this due to deficit in forming associations or working memory?
working memory vs associative memory - delayed response task
- food is paired with a visual cue
- task measures animals ability to retain long-term rules
- no need for animal to retain visuospatial info during delay
- PFC lesions do not damage this ability (only damage WM task)
response of PFC neurones in delay response task
- prefrontal neurons differentially respond to stages of experiment (cue-delay-response)
- neurones active during delay period - these neurons provide neural correlate for retaining visuo-spatial info
how long do PFC neurons stay active for in delay-response-task
until they give response (varied with each task)
PFC in working memory for faces (Druzgal and D’Esposito, 2003) - PROCEDURE
- four stimuli presneted successively in encoding section - either intact or scrambled faces
- Ps had to remember only inatct faces
- number of intact faces varied with each trial (more faces.= more demands on WM)
- probe presented was either a match or not
