Chapter 5 reading
PSY270 Lecture 5
Short-Term and Working Memory
Memory: process involved in retaining, retrieving and using information about stimuli, images, events,
ideas and skills after the original information is no longer present.
Clive Wearing: lost of memory due to brain damage. Remembers what just happens and forgets
everything else 3 minutes later.
Atkinson & Shiffrin: modal of memory
Sensory memory -> short term memory -> Long term memory
sensory memory: holds all incoming info for fractions of a second – second
STM: 5 – 7 items for 15-13 seconds
LTM: large amount of info.
•controlled process: rehearsal of stimulus, strategies to make memorable, strategies of attention to
•encoding: process of storing information
Sparkler’s Trail and projector’s shutter
eg. Ligh ts from fir eworks cre a te a tr ail – cre a tion of mi n d, p ersists in vision.
persistenc e of visio n: retention of p erc e pti o n of light in mi n d .
Sperling: me a s ured c a pa city an d d u ratio n of s e nsory store
fla s hed ar r ay of lett ers for 5 0 millis e c onds an d a s ked to rep or t a s many a s p os sible
wh ole rep o r t meth o d : rep or t a s much a s p o s sible
average 4.5 o u t of 1 2 let t ers.
Par ti al rep o r t method: at t entio n dir e c ted to o n e row
oHigh – to p
oMedium – mi d dle
oLow – b o t t om
oDelayed par ti al rep or t method: rep or t ed le s s.
Shor t lived s e nsory memory registers all or most of information that hit s visual re c e ptors, b ut
de c a ys wit hin le s s than a s e c ond
Sensory memory is large, b ut d u ration is brief.
Iconic memory / visual ico n – brief s e nsory memory for visual sti m uli
Echoic memory – p ersistenc e of so u n d , lasts for few s e c onds.
Short term memory (STM):
re c all te s t: p ar ticipants pre s e nted wit h sti m uli an d aft er d elay a s ked to remember a s much a s
p o s sible
Brown, Peterson & Peterso n : p ar ticipants re a d n u mber / lett ers, others h ave to remember the
lett ers. When h e a r n u mber, repe a t an d count b a ckwards b y 3 s.
oDec ay : forgot lett ers
Kepp el & Und erwo o d: sugge s ted n ot d u e to d e c a y, b ut to “proa c tive inferenc e ”(PI)
oPI: interf erenc e that o c c urs when info le arned previo u sly interfere s wit h le arnin g n ew
oRec allin g e a rly lett ers in list c a us e d interferenc e making it difficult to remember later
lett ers in the list.
Duration when rehe a rs al is prevented is 15-20s e c onds.
PSY270 Lecture 5
digit span: typically 5-8 digits can be remembered.
Miller: magic nu mber 7 +/- 2
Cowan: 4 items
oLuck & Vogel: flashed two arrays of colored squares separated by delay
Second same as first?
Performance near perfect when 1-3 squares, decreased with 4+
STM = 4.
oEricsson et al: de monstrated chunking allowed SF to remember a lot
Runner, recoded digits into larger units with meaningful sequences
Chunks based on knowledge of running times (in his LTM)
oChase & Simon: chess player arrangments
Experienced could remember positions
No advantage if master can’t chunk.
How is information coded (STM)?
physiological approach to coding: how stimulus is represented by firing of neurons
mental approach to coding: how a stimulus/experience represented in mind
auditory: based on sounds
oConrad: participants saw number of target letters, told to write down letters in order
Made errors when misidentified target letter as another (sounds similar)
Code for STM is auditory rather than visual – eg. telephone numbers
Visual: visually, eg. remembered layouts
oSala et al: par ticipants asked to look at pat tern (white/black grid) and indicate which
squares blacked out.
Able to complete average of 9 shaded squares before making mistakes
oWickens et al: conditions – fruits or professions
Participants listened to 3 words, counted backwards 15 secs and recall
Presented other group’s words/different category.
•Decreases proactive interference
Release from PI depends on categories (involves meaning of words)
Working Memory (Baddeley)
limited capacity system for temporary storage and manipulation of information for complex tasks
such as comprehension, learning and reasoning.
STM concerned with storing information for brief period of time, working is concerned with
manipulation of information occurring in complex cognition
STM – single component. Working – number of components.
Phonological loop: keeps verbal and auditory information.
oStore – limited capacity, holds information for few seconds
oArticulatory rehearsal process: responsible for rehearsal, keep items in phonological store
Visuospatial sketch pad: holds visual and spatial information
Central executive: major work of working memory occurs.
oPulls info from LTM and coordinates activity oh phonological loop and visuospatial
oDecides how to divide attention
PSY270 Lecture 5
phonological similarity effect: confusion of letters/words that sound similar
Word length effect: memory for short list better than long
Articulatory suppression: reduces memory because speaking interfere with rehearsal
Visuospatial sketch pad
visual imagery: creation of visual images in mind in absence of physical visual stimulus
Shepard & Metzler: measure reaction time whether pair of objects the same.
oWhen separated 40 degrees, took 2 seconds to decide
o14 0 degrees, 4 seconds.
oReaction time longer for greater differences in orientation
oMental rotation: some participants using this to solve problem
Brooks: interference affect operation of visuospatial sketch pad
oImagine “F” and point/say “out ” or “ in”. Pointing task is difficult – overload
component makes working memory “working ”
control center, atten tion controller
patients with frontal lobe damage have problems controlling attention
opreservation: repeatedly performing same behavior even if it is not achieving desired goal
(works well if rule stays the same)
store information (provide extra capacity) and is connected to the LTM.
Still work in progress – Baddeley said concept is still in early develop men t.
Working memory and the brain
Effect of damage to prefrontal cortex
holds information for brief periods of time.
Goldman-Rakic: monkey experiment on delayed-response task
oPerformance drops if prefrontal cortex removed (select correct food)
Prefrontal neurons that hold information
Funahashi et al: experiment record neurons in monkey’s PF while doing delayed response task
oNeurons that responded only when square was flashed in a particular location
oNeurons continued responding during t he delay.
oFiring of neurons indicates object was presented at a particular place.
PF cortex may be area closely associated with working memory.
Brain activation in hu mans
PF cortex and other areas are activated.
PF, frontal lobe, parietal lobe and cerebellum
Vogel et al: experiment on allocation of attention by measuring event related potential in humans
oLarger ERP indicated more space used in working memory
oLower memory capacity group held fewer items in working memory than high memory
oSome people’s central executive are better at allocating attention than others.
More efficient working memories likely to perform well on tests of reading,
reasoning ability and tests to measure intelligence.