1. PSY 323: Cognition
Chapter 5:
Short-Term & Working Memory

2. Memory
Memory
Processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present

3. Modal Model of Memory Atkinson & Shiffrin (1968)
Three Stage Modal Model
Sensory Memory
Short-Term Memory (working memory)
Long-term memory (permastore)

4. Sensory Memory
Major function is to hold info long enough so that it can be processed
Sight (usually less than a second)
Sound (a little longer - maybe up to 2-3 seconds)

5. Sensory Memory
Persistence of vision: retention of the perception of light
Sparkler’s trail of light
Frames in film

6. Also referred to as “Transient Memories”
Visual sensory memory
The iconic store
Auditory sensory memory
The echoic store

7. Measuring Sensory Memory
How big is sensory memory?
Sperling (1960)
Array of letters flashed quickly on a screen
Participants asked to report as many as possible

8. Testing Iconic Memory
Sperling’s whole and partial report procedures present participants with a different 3 x 4 matrix of unrelated consonants (a total of 12) for 50 ms across numerous experimental trials
Here is an example: X M L T A F N B C D Z P

9. Demo:
Get ready…

10. Demo: Sperling (1960 ): Full ReportJ M O R P Z K Y C T B U

11. Demo:
Get ready…

12. Demo: Sperling (1960): Partial ReportW E G D S C F

13. Testing Iconic Memory
In the whole-report procedure participants had to report the entire matrix
Participants said they sensed the entire matrix but that it had faded from memory before they could report all 12 letters

14. Testing Iconic Memory
In the partial-report procedure, the participants had to report only one row of the matrix, a row indicated by an auditory cue on each trial
When the auditory cue was given immediately after the brief presentation of the letter matrix, participants recalled the indicated row approximately 82% of the time
When there was a one second delay between presentation of the matrix and the auditory cue, participants’ recall of the cued row worsened (about 38%)

15. Sensory Memory
Whole report: participants asked to report as many as could be seen
Report average of 4.5 out of 12 letters
Partial report: participants heard tone which told them which row of letters to report
Report average of 3.3 out of 4 letters
Sperling (1960)

16. Iconic Memory Is an exact copy of visual information
Less than a second in duration
Very large capacity
Consider the example of a cartoon movie, which is nothing more than a series of still drawings flashed in rapid succession
Iconic memory allows us to perceive motion in the drawings

17. Auditory Sensory Memory
Several studies have shown analogous results in auditory memory…
Echoic store studies often use dichotic listening

18. Short-term Memory Short-Term Memory (STM)
Psychology 101 On Line
Short-term Memory
Short-Term Memory (STM)
A limited capacity memory system involved in the retention of information for brief periods; it is also used to hold information retrieved from long-term memory for temporary use

19. Duration of STM
Researchers differ saying that without maintenance rehearsal something stays in STM for between 6-30 seconds
After this its either lost forever or somehow makes its way into LTM
Zhang & Luck (2009)
15-20 seconds or less

20. STM Tasks See next slide 
Brown-Peterson Distractor Task (Brown, 1958; Peterson & Peterson, 1959)
Procedure
Read three letters, then a number
Begin counting backwards by 3’s
Counting backwards prevented the rehearsal of the letters
After a set time, recall three letters
Results
Recall drops dramatically after just a few seconds
See next slide 

21. Brown-Peterson Distractor Task
Results
Peterson & Peterson (1959)
3 sec delay  recall rate 80% 18 sec delay  recall rate 12%

22. Can intereference occur in STM?
Keppel & Underwood (1962)
They saw that on the first trial, memory performance was nearly perfect
As subjects participated in more trials their performance declined
Their conclusion: previous trials interfered with later trials – proactive interference

23. Brown-Peterson Distractor Task
Why the quick forgetting?
Memory trace vanished because of decay during the passage of time after hearing the letters
Closely spaced trials lead to poorer recall; susceptibility to interference
Proactive Interference seems to be a problem
Cumulative memory seems to be occurring as memory form previous lists may be hampering recall
Information learned previously interferes with learning new information: seems to build up across trials

24. Types of Interference Proactive Interference Retroactive Interference
The disruptive effect of prior learning on the recall of new information (old materials increasing the forgetting of new materials)
Retroactive Interference
The disruptive effect of new information on the recall of previous information (new materials increasing the forgetting of old materials)
Time Time Test Interference
Study French Study Spanish Recall Spanish Proactive
Study French Study Spanish Recall French Retroactive

25. Capacity of STM: How many items can be held in STM
Digit Span
Miller (1956)
7 +/- 2 meaningful groupings
George Miller
( )
“The Magic Number”

26. How accurate is the magic number?
It is accurate for relatively simple information groups digits, words, etc.
Not as accurate for more complex information
Example: with 3 or 4 word phrases the magic number becomes 3 to 5

27. How accurate is the magic number?
Luck & Vogel (1997)
Procedure
Participant sees the first display and then indicates whether the second display is the same or different

28. How accurate is the magic number?
Luck & Vogel (1997)
Results
Participants were almost perfect when the researchers presented 1-3 squares but then performance began decreasing when four or more squares were presented
Interpretation
People are able to retain about four items in their STM

29. Chunking Helps Increase Limited Capacity
Ericcson et al. (1989)
College student had an initial digit span of 7
After 230 one-hour training sessions for 2 years, he could remember up to 79 digits
How did he do it?
Combing the numbers with meaningful sets:
 world record for mile (3 min 49.2 sec)
 almost emergency (9 1 1)
 very old man (89.3)

30. NBCADDCBSNYY (NBC) (ADD) (CBS) (NYY)
Chunking Example
NBCADDCBSNYY (NBC) (ADD) (CBS) (NYY)

31. Control Processing
Active processes (effortful) that are initiated by the person
Mental Rehearsal
Maintenance Rehearsal
Repeating things over and over
Spacing effect
Elaborate Rehearsal
Involves thinking about how new material relates to information already stored in memory

32. Working Memory
Refers to the system for temporarily maintaining mental representations that are relevant to the performance of a cognitive task in an activated state
Reading span measures the capacity of working memory when attention must be paid to comprehension of sentences and to remembering a list of words

33. WM is different from STM
Working memory consists of a number of parts
Working memory helps us manipulate information to carry out complex tasks, not just store information
Baddeley & Hitch (1974)

34. Models of Working Memory
Baddeley & Hitch (1974)
Proposed a phonological loop and a visual-spatial sketch pad coordinated by a central executive
The loop stores and rehearses verbal representations whereas the sketch pad does the same for visual/spatial representations
Central executive focuses and switches attention, supervises and coordinates the storage components, and retrieves representations from long-term memory

35. So what is WM made of?
Three components to WM
Baddeley & Hitch (1974)

36. Three Components to WM Baddeley & Hitch (1974) The central executive
coordinates verbal and visual information
Divide attention between different tasks
Help focus your attention
Baddeley & Hitch (1974)

37. Phonological Loop Holds verbal and auditory information
STM primarily uses auditory coding
Made of two parts
Storage - Passive, holds information
Decays in about 2 seconds without rehearsal
Rehearsal - Active, repeats information in storage to prevent decay
See next slide 

38. Phonological Loop: Phonological Similarity Effect
Conrad (1964)
Letters or words of similar sounds get confused
See next slide 

39. Phonological similarity effect demo…
Memorize the following words:
mac can cap man map
Now, write them down.
Memorize the following words:
pen pay cow bar rig
Now, write them down.
Conrad (1964)

40. How did you do? mac can cap man map pen pay cow bar rig
People usually do better with List 2
Why? List 1 has words that sound really similar
Conrad (1964)

41. Word-Length Effect Baddeley et al. (1984)
Memory for lists of words is better for short words than for long words
It takes longer to rehearse long words and to produce them during recall

42. Demo: Which is more difficult?
Read the following words, look away, count up to 15, and recall.
Beast, bronze, wife, golf, inn, limp, dirt, star
Alcohol, property, amplifier, officer, gallery, mosquito, orchestra, bricklayer
Baddeley et al. (1984)

43. The word-length effect
It takes longer to rehearse long words
That’s why it is difficult to memorize
Baddeley et al. (1984)

44. Articulatory Suppression
Prevent one from rehearsing items to be remembered
Reduces memory span
Eliminates word-length effect
Reduces phonological similarity effect for reading words

45. Demo: Which is more difficult?
Read the following words while repeating the word “the” out loud (the, the, the…), look away, count up to 15, and recall.
automobile apartment syllogism basketball
Read the following words while repeating the word “la” out loud (the, the, the…), look away, count up to 15, and recall.
story car towel coffee swing
Baddeley et al. (1984)

46. Phonological Loop: Articulatory suppression
Articulatory suppression: Speaking interferes with the operation of the loop
“the, the, the…”
“la, la, la, la, la,…”

47. Articulatory Suppression
Baddeley et al. (1984)
Two word lists are spoken and must be remembered
automobile apartment syllogism basketball
story car towel coffee swing
Second list should be easier - it’s shorter
But Baddeley had subjects say the word “the” over and over again

48. “the, the, the, the, the…” “the, the, the…” prevents rehearsal
Word-length effect is abolished
Baddeley et al. (1984)

49. Visuospatial Sketch Pad
Holds visual and spatial information; used in doing anything visual - puzzles, drawings, etc.
Shepard and Metzler (1971)
Mental chronometry – general idea of measuring how long it takes to carry out various cognitive tasks
Task: participants saw two objects, had to indicate quickly whether the two objects were the same or different

50. Central Executive Pulls information from LTM and coordinates tasks
Uses information from the phonological loop and visuospatial sketchpad
Focuses on specific parts of task
Switches attention from one part to another
Attention controller

51. Working Memory & The Brain
Prefrontal Cortex Damage
Goldman & Rakic (1992)
Procedure: Delayed Response Task
Monkey see food reward in one of two food wells; screen is lowered; delay
Holding information and then required to make a response after time delay
Results
No problem remembering unless prefrontal cortex is removed (only at chance levels for these monkeys)
Interpretation
Strong evidence that prefrontal memory is integral to working memory

52. Prefrontal Neurons
Funahashi et al. (1989)

53. Credits
Some of the slides in this presentation prepared with the assistance of the following web sites: