task 1 Flashcards
Atkinson’s & Shiffrin’s model
–> three distinctions among different kinds of memory
- sensory memory:
- brief/transient sensations of what just has been perceived
- information automatically/rapidly decays
- -> information first flows into this memory - short-term memory (STM)
- temporary memory
- can be maintained as long as its rehearsed/consciously attended to
- -> elements of sensory information that are attended to are transitioned to STM - long-term memory (LTM)
- memories can be retained for long periods/permanently without requiring ongoing maintenance/conscious attention
- -> memories go through process in STM and in some cases are transferred into LTM
=> CRITICISM:
- when STM is damaged still some memories get stored in the LTM
- doesn’t specify depth of processing needed
transient memory
- nonpermanent memory that lasts seconds/minutes
- in Atkinson-Shiffrin model they correspond to the first two stages (sensory/STM)
sensory memory
- sensory memory for every sensory modality
- lasting very briefly
- -> captures raw incoming sensory stimuli and passes it to STM store
STM
- once sensory memory is recognised/registered > STM maintains information temporarily through active rehearsal
- incoming information > sensory based iconic memory > STM if maintained through active rehearsal
- ability to hold information limited:
- -> limited in capacity: range from 5 to 9 items
- -> limited to what we can pay attention to
iconic memory
critical for recognising and processing briefly present information
Sperling task
–> sensory memory
- people are presented with 3x4 visual array
- once latter is removed: one of three tones is played (high/medium/low) corresponding to the rows
- participants are indicated to report row corresponding to tone
–> 75% of letters are recalled (rather than 30-40% total array)
=> ICONIC MEMORY: persist for very short time but includes all items recently seen
transferring information from STM to LTM
- repeated rehearsal is required to maintain information in STM but doesn’t ensure long-term storing
- Depth of Processing: level of activity devoted to processing information
- the MORE ACTIVELY we process new information (e.g. applying meaningful connections) the MORE LIKELY we are to remember it
- passive rehearsal: good for STM but not sufficient for transferring information LTM
working memory
- goal-directed
- involves temporary retention of information just experienced (sensory memory) or just retrieved from LTM
Baddeley’s model of working memory
- consists of “central executive” that controls two memory buffers:
- -> visuospatial sketchpat (VSS) > stores object/location material
- -> phonological loop (PL) > stores verbal material
- —> both are stored separately
- distinction between two processes:
- -> manipulation
- -> maintenance
Baddeley’s model
–> MANIPULATION
- depends on central executive
- involves:
- -> adding/deleting/selecting among items to guide behaviour
- -> retrieving information from LTM
- -> transferring it from VSS and PL to LTM (??)
Baddeley’s model
–> MAINTENANCE
requires rehearsal of information in two memory buffers
visuospatial sketchpat (VSS)
- mental workspace for storing/manipulating both visual and spatial information
- limited in its capacity
- -> delayed nonmatch-to-sample task
delayed nonmatch-to-sample task
- monkey’s shown sample object and finds reward under it
- delay period: monkey’s view on test object is blocked
- food reward is hidden under new object ≠ original sample
- monkey chooses non-matching
> must learn to remember which unique sample was seen previously
must hold this information in visuospatial memory until presented with choice
phonological loop (PL)
- maintains auditory memories by means of internal speech rehearsal
- average phonological loop can retain 2 seconds worth of speech
- internal/unspoken speech used during rehearsal is key to PL and working memory
- -> if internal rehearsal is interrupted > storage cannot occur
- -> internal speech proceeds at same rate as speech spoken aloud
- word-length effect:
- -> as length of words increases, number of rememberable words declines
Baddley’s model
–> relation of VSS and PL
> dual-task experiment:
- participants imagine a “*” travelling along the edges of an “F”
- whenever it turned a corner the participant had to signal whether it was an extreme or intermediate corner
- therefor, participants were separated into 3 groups:
- > vocal group (“yes”/”no”) > fastest reaction time
- > tapping (once/twice) > intermediate reaction time
- > pointing (“Y”/”N”) > lowest reaction time
=> reaction times showed that the two capacities are independent of each other = filling up one does not affect capacity of the other
main functions of central executive (4)
- controlled updating of STM buffers
- setting goals and planning
- task switching
- stimulus selection and response inhibition
main functions of the central executive
–> CONTROLLED UPDATING OF STM BUFFERS
- does so by:
- -> receiving/evaluating sensory information
- -> moving items into & retrieving from the LTM
- -> deciding which memories are needed for which task
> N-BAK TASK
- participant needs to remember N cards previously as the one presented atm
PETRIDES’ SELF-ORDERED MEMORY TASK
- participant needs to point at different items on every card with the same target set
main functions of the central executive
–> SETTING GOALS AND PLANNING
- keeping track of goals
- planning how to achieve them
- determining priorities
> TOWER OF HANOI
- solving requires a lot of manipulation of working memory because we must remember:
(1) what subgoals have been ACCOMPLISHED
(2) what subgoals REMAIN
(3) what is next subgoal to be ADDRESSED
main functions of the central executive
–> TASK SWITCHING
- requires manipulation of working memory
- -> we must pay ATTENTION to ONGOING TASK while MONITORING EXTERNAL CUES for information that may signal need to SWITCH to another TASK
> WISCONSIN CARD SORT TEST:
- participant needs to sort card based on shape/colour/number while experimenter switches between rules of sorting
main functions of the central executive
–> STIMULUS SELECTION AND RESPONSE INHIBITION
- central executive allows:
- -> to inhibit a habitual response
- -> to shift attention to alternative/context-specific rule that we must remember
> STROOP TASK:
- participant needs to read a list of written colours (“red”/”blue”/etc.) but has to say out loud what colour those words are written as
behavioural consequences of frontal-lobe damage
- show deficits on all working-memory/executive-control tasks
- in absence of executive-control system:
- -> we are no longer guided by long-term goals/task-specific constraints
- DYSEXECUTIVE SYNDROME:
–> disrupted ability to think/plan/organise
–> can be due to tumors/surgery/strokes
» people become impulsive/easily influenced by momentary urges/ highly distractable - Wisconsin card sort test to assess frontal-lobe function
- -> patients can learn initial sorting rule but are impaired at making transition = PERSEVERATION
Goldman-Rakic’s eye gaze test
- many PREFRONTAL-CORTEX NEURONES FIRE only during DELAY PERIOD when animals are required to maintain information about spatial location of object
=> SUGGESTING: PFC holds in information needed to make later response
mapping Baddeley’s model onto PFC anatomy
dorsal and ventral regions of PFC perform qualitatively different processes:
VENTROLATERAL PFC:
- supports encoding/retrieval of information
- -> performing roles of VSS/PL (acc. to Baddeley’s model)
- during encoding of new semantic information:
- -> anterior regions: activated during tasks involving semantic processing
- -> posterior regions: activated during phonological processing
DORSOLATERAL PFC:
- supports higher-order executive-control: monitoring/manipulating stored information
- -> central exectuive (acc. to Baddeley’s model)
- dominant roles:
- -> right DLPFC: monitoring processes
- -> left DLPFC: verbal materials
LESIONS
- produce severe deficits in temporal ordering which requires active manipulation of working memory
- -> patients may show impairment in delay-response tasks
mapping Baddeley’s model onto PFC anatomy
–> ANATOMICAL DISTINCTION BETWEEN VSS & PL
- language tends to be left-lateralised in brain
- -> damage to left PFC: deficits in verbal working memory
SPATIAL WORKING-MEMORY TASK (Smith & Jonides):
1. patients are presented with three dots arranged in random locations on display screen
2. delay period: dots disappear for 3 seconds
3. circle appears somewhere on screen
4. participant indicates if circle contains location of one of the previous dots
- experimental group: involves spatial memory & ability to encode spatial information
- control group: involves perceptual processing/not working memory
» spatial location tasks activate region in right hemisphere of premotor cortex
» object-identity tasks activate right DLPFC
=> spatial &object working memory are localised differently
clinical perspective
–> SCHIZOPHRENIA
- disturbance in working memory & executive control
- -> DLPFC is dysfunctional / VLPFC is unimpaired
- dopamine alters neurone-to-neurone communication
–> patients have more D1 receptors in DLPFC than healthy people (try to compensate lack of dopamine release)
–> patients with lots of D1 receptors show worst performance on assessment of working memory
» link between dopamine regulation of DLPFC & working memory - COMT genes affect dopamine metabolism in frontal lobes
–> genetic mutations affecting dopamine activity in PFC are related to emergence of cognitive deficits seen in schizophrenia - MUTATION of ONE KIND OF GENE causes SMALL CHANGE in cognitive performance / mutations in DIFFERENT KINDS OF GENES puts someone in HIGH-RISK category for schizophrenia
» the more copies of COMT genes > the less prefrontal activity
clinical perspective
–> ADHD
- difficulty with working memory/executive control processes
- involves dysfunction in PFC and its cortical/subcortical connections (incl. cerebellum/basal ganglia)
- -> smaller right PFC region associated with spatial attention/working memory
- genes associated with ADHD regulate function of dopamine in brain
–> medications for ADHD alter (positively) dopamine function in cortex
» effects are temporary
three fundamental processes
ENCODING:
- information is translated into a mentally processable form
- we label it in various ways, before placing it into memory
» memory code:
–> is formed when information has been encoded in some manner
–> once information is transformed into memory code, it is stored
STORAGE:
- information is maintained in memory for some period of time
» memory store:
–> mental location in which encoded information is held
RETRIEVAL:
- information is activated in a way that can influence other mental events/behaviour
- -> if we cannot access information: encoded & stored information will not affect our cognitions/emotions/behaviours
ARTICLE: Fuster & Alexander
–> neurone activity related to short-term memory
PROCEDURE
- monkeys were trained and tested in performance of delayed response task
1. sitting in front of test objects
2. test objects: two identical wooden blocks
3. cue period: monkey is presented with an apple that is put under one of the wooden blocks
4. delay period: immediately after the monkeys sight is blocked
5. response period: monkey can choose one object > if correct it can have reward
ARTICLE: Fuster & Alexander
–> neurone activity related to short-term memory
FINDINGS
- changes in firing frequency during DELAYED RESPONSE TASK:
- -> most cells increase firing during cue presentation period or at beginning of ensuing delay
- increased firing was in some units preceded by inhibitory phase
- temporal patterns of firing frequency seen in prefrontal/thalamisc units during cue & delay periods
» participation of these units in ACQUISITION and TEMPORARY STORAGE of SENSORY INFORMATION - excitatory reaction of neurones in MD (thalamus) & frontal cortex during delay response trials are related to FOCUSING OF ATTENTION on information placed in temporary memory storage for prospective utilisation
- NO correlation was found between EYE MOVEMENT and UNIT ACTIVITY in areas of brain explored
brain substrates of working memory
DORSOLATERAL PFC
» central executive
RIGHT VENTROLATERAL PFC
» visiospatial sketchpad
LEFT VENTROLATERAL PFC
» phonological loop
–> ANTERIOR: semantic information
–> POSTERIOR: phonological information
RIGHT POSTERIOR CORTICAL VISUAL AREAS
» object & location information
LEFT POSTERIOR CORTICAL SPEECH & LANGUAGE AREAS
» verbal information
=> STORAGE
