1. CLPS0020: Introduction to Cognitive Science
Short Term Memory
CLPS0020: Introduction to Cognitive Science
Professor Dave Sobel
Fall 2016

2. Modal Model
Short Term Memory is a “loading dock” outside the “warehouse” of Long Term Memory
Limited Capacity and Duration
Long Term Memory
Short Term Memory
Visual/Auditory representation of knowledge (perceptual), can be processed to something more conceptual, and doing so encodes information into long term memory

3. Serial Position Curve I’d like you to remember a list of words
Don’t take notes
Pencil
Apple
Rooster
Button
Bookbag
Finger
Table
Bottle
Hammer
Rainbow
Speaker
Package
Razor
Computer
Peanut
Coffee
Poster
Airplane
Bathtub
Grandma
List of Words
Pencil Shirt
Apple Airplane
Finger Computer
Stapler Wire
Rooster
Button
Bookbag
Rainbow
Bathtub
Package
Grandma
Bottle
Razor
Coffee
Knife

4. Serial Position Curve
Draw out position curve based on the list of words
Pencil
Apple
Rooster
Button
Bookbag
Finger
Table
Bottle
Hammer
Rainbow
Speaker
Package
Razor
Computer
Peanut
Coffee
Poster
Airplane
Bathtub
Grandma
List of Words
Pencil Shirt
Apple Airplane
Finger Computer
Stapler Wire
Rooster
Button
Bookbag
Rainbow
Bathtub
Package
Grandma
Bottle
Razor
Coffee
Knife

5. Idealized Serial Position Curve
Primacy Effect
Recency Effect

6. Procedure and Findings
Free Recall Procedure (Deese & Kaufman, 1957; Glanzer & Cunitz, 1966)
People are asked to learn a list of words, then asked to repeat back as many as they can.
Free to recall the words in any order
Effects
People tend to remember the first few words (Primacy)
People tend to remember the last few words (Recency)

7. Explanations Recency Effect Primacy Effect
No new information is coming into STM. The items that are currently in STM are recalled
Primacy Effect
When the first word is presented, it’s the only thing in STM. It gets all the maintenance. Second word gets 50%, etc.
There is enough rehearsal to encode the first few words into LTM, but not the middle words

8. Further Tests
If the recency effect is caused by items in residual STM, then it should be eliminated if we occupy STM (Baddeley & Hitch, 1977)
Immediately after learning perform a working memory task (count backwards by 3 from 70)
Primacy effect remains
Recency effect is eliminated

9. Further Tests(2) Rate of presentation (Sumby, 1963) Taboo Words
Slower presentation of words (more maintenance time) improves overall accuracy and primacy effect, but not recency effect
Taboo Words
In our case: Computer (why?)
You can think of other cases

10. Thoughts so far Conclusions are apropos of the modal model
Primacy and Recency Effects
Auditory basis?
Rate of presentation in SPC
Word-length effect
Digit Span capacity across languages
Japanese (Longer Digit Span)
Turkish (Shorter Digit Span)
Digit span tasks causes the “speech” areas of the brain to activate (Smith, 2000)

11. Beyond the Modal Modal Working Memory is a dynamic part of LTM
Long Term Memory
Working Memory
Working Memory
Working Memory is a system within LTM, which interacts with attention

12. Active Span & Cognitive Control
Ability to operate on information during memory process (even if you’re unaware that it’s a memory process)
Demonstration: What was the first word of the last 3 sentences I said?
Or: Try to do free recall procedure while performing long division

13. Why is this important?
Reflects the ability to encode info into LTM, as well as shift WM around
Active Span correlates with certain outcome measures better than “Static span” measures - like digit span
SAT Scores, Logical Reasoning Tests, Reading Comprehension
Conclusion: Working memory might be more than rehearsal (Keep this in mind over the next few lectures!)
Also the active processing of information (Awareness)