Transcript Working Memory

Working Memory
Dr. Claudia J. Stanny
EXP 4507
Memory & Cognition
Spring 2009
Models of Immediate Memory
Primary & Secondary Memory (James, 1890)
“Modal Model” (Atkinson & Shiffrin, 1968)
• Sensory Registers / Sensory Memory
• Short-Term Memory
• Long-Term Memory
Working Memory (Baddeley & Hitch, 1974)
Claudia J. Stanny
2
“Classic” Research on Working
Memory
George Miller (1956)
• “Magical Number Seven” article and concept of
chunking
Brown (1958) & Peterson & Peterson (1959)
• Very rapid forgetting of perfectly learned
information
• Recency effects & Serial position effects in the
recall of lists of words
Claudia J. Stanny
3
Brown-Peterson Task
Present a small amount of information to
remember: e.g., a consonant trigram
• X J Q
Present a 3-digit number and ask subject to
count backwards by 3s during the retention
interval
• 987 . . . 984 . . . 981 . . . 978 . . . 975 . . . 972 . . .
Recall the consonant trigram
• ???
Claudia J. Stanny
4
Recall Performance in the
Brown-Peterson Task
Claudia J. Stanny
5
Serial Position Effects
Present lists of 15 or more words
Free recall of words immediately after each list
Plot the number of words recalled from each
serial position in the list
Recall of all words from all lists following a filled
delay produces a different pattern of recall
Claudia J. Stanny
6
Typical Serial Position Effects Data
Claudia J. Stanny
7
Claudia J. Stanny
8
Characteristics of Short-Term Memory
Limited capacity (George Miller, 1956)
• 7±2
• Effects of chunking
Limited duration
• 20 sec or less if no rehearsal is done
Type of coding: Verbal/Acoustic
Proposed mechanism for information loss
• Decay
• Interference
Factors that Influence the Capacity
of Working Memory
Chunking
• Capacity limited to 7 plus or minus 2 chunks
Number of rehearsals & type of rehearsal used
Pronunciation time
• Cross-language comparisons: Digit span decreases
with longer pronunciation times
Semantic similarity
• Proactive Interference
• Release from proactive interference (Wickens,
1976)
Claudia J. Stanny
10
Release from PI
Brown-Peterson Task
Wickens (1976)
Working Memory
Conceptualizes immediate memory as a
complex system with independent
components
Klatzky’s (1975) STM as a workbench
• Trade-off between storage capacity and
processing capacity
Working memory more than a passive storage
system – management of information coding
and use
Claudia J. Stanny
12
(model proposed
in 1974)
Characteristics of WM Components
Phonological Loop
•
•
•
•
Auditory/Acoustic coding
Effects of time required to pronounce words
Effects of unattended speech
Effects of articulatory suppression
Visuospatial Sketch Pad
• Visual and spatial coding
• Interfering effects of competing spatial tasks
Central Executive
• Regulation and coordination of specialized
systems; attentional control
Working Memory Model
Claudia J. Stanny
15
Phonological Loop
Acoustic confusion errors suggest acoustic codes
• Errors in recall dominated by acoustically similar
letters
Maintain information about order and
sequencing in problem-solving tasks
Supports cognitive processes for reading
Phonological tasks activate frontal & left
temporal lobe
Claudia J. Stanny
16
Research on the Phonological Loop
Effects of time required to pronounce words
• Digit span increases as pronunciation time
decreases
• Recall of single-syllable vs multi-syllable words
• Limited capacity in terms of pronunciation time
Effects of unattended speech
• Irrelevant speech disrupts performance on
memory for verbal stimuli
Effects of articulatory suppression
• Repeating an irrelevant word (doh – doh – doh)
during study disrupts memory performance
Claudia J. Stanny
17
Visuospatial Sketchpad
Visual scenes and images generated from verbal
descriptions or long-term representations
Limited capacity
• based on spatial characteristics
Function of the visuospatial sketchpad
• Navigation
• Spatial tasks (mazes, video games, etc.)
Claudia J. Stanny
18
Central Executive
Closely associated with conscious awareness
Manages allocation and switching of attention
Not a storage system itself:
• Retrieves information from specialized storage
systems, manipulates & modifies this information
Suppresses irrelevant information
• Enables focus on current processing task
• Random number generation task
loss of attentional control leads to predictable patterns
in numbers generated
Claudia J. Stanny
19
Episodic Buffer
Limited capacity temporary storage area
“Workspace” for working memory
• Mental modeling of the environment
• Problem-solving activities
Integrates and binds information from several
sources using a multi-modal code
• Phonological loop
• Visuospatial sketch pad
• Long-term memory
Claudia J. Stanny
20
Clinical Depression and Memory
Symptoms include:
• Problems with concentration
• Difficulty suppressing negative thoughts
Evidence of reduced function in WM:
• Deficits observed related to interference during an
articulatory suppression task
• Lower recall of visual information
• Some evidence of reduced executive function
Claudia J. Stanny
21