Working Memory

Dr. Claudia J. StannyEXP 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)

2Claudia J. Stanny

“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 TaskPresent 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 theBrown-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

8Claudia J. Stanny

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/AcousticProposed 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 usedPronunciation 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 ComponentsPhonological 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 readingPhonological tasks activate frontal & left

temporal lobe

Claudia J. Stanny 16

Research on the Phonological LoopEffects 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 performanceClaudia 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 ExecutiveClosely associated with conscious awarenessManages allocation and switching of attentionNot a storage system itself:• Retrieves information from specialized storage

systems, manipulates & modifies this informationSuppresses 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 BufferLimited 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