Article summary

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Article summary

• You will summarize and critique one research
  article from recent cognitive psychology
  literature (since 1998).
• The length should be no less than two and a half,
  double-spaced typed pages.
• Use Times New Roman 10-12 point font with 1-inch
  margins.
• The required length does not include spacing from
  the title.
• Turn in a copy of the first page (i.e. title page
  with abstract, authors, etc.) of the actual
  article with your summary.
• I will find the article online and do not want a
  big pile of papers.
• Summaries turned in late will receive one full
  letter grade deduction for each week they are
  turned in late.
• For example, papers turned in up to one week late
  will receive a B grade at best.

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Article Summary Grading

• I will evaluate your ability to clearly
• (a) identify the research question,
• (b) identify the independent and dependent
  variables,
• (c) summarize the results
• (d) summarize the researcher(s) conclusions.
• (e) your evaluation of the method
• (f) your evaluation of the authors conclusion
• (g) larger implications of the research.
• Do not simply answer each of the above in a list
  of bullet points. Try to write the summary as if
  you are verbally telling someone about the
  article (because you are).
• I will take off points for poor grammar and
  spelling.
• I am willing to look at drafts of your summary
  before it is due (until Sunday evening).

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Short-Term Working Memory

• March 2, 2005
• Brandon Beltz

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What is Memory?

• The process of acquiring and retaining
  information for later retrieval
• The mental storage system involved in these
  processes.

5
Why is memory important?
6
Memory The Big Picture
W. W. Norton
7
Synonyms for Short Term Memory

• Working Memory
• Immediate Memory
• Elementary Memory
• Short-term Store
• Temporary Memory
• Primary Memory

8
Short Term versus Working Memory

• Short Term Memory (STM)
• Older term emphasizing input and storage of new
  information.
• Example Remembering a phone number
• Working Memory (WM)
• Newer term emphasizing processing (work) and
  storage.
• The mental workbench.
• Example Solving an arithmetic problem in your
  head
• However, there are no clear distinctions between
  the two terms.

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Aspects of STM and WM

• Where active mental effort is expended.
• Where comprehension takes place.
• Often associated with attention and
  consciousness.
• Can eventually lead to long-term memory.

10
Short Term Memory Limitations

• Amount of information storage
• Limited capacity bottleneck
• Duration (time) of information storage
• Interference and decay

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Limited Capacity Bottleneck

• There is a limit to the amount of input that can
  be stored.
• Hmmm, this theme sounds familiar. Remember
  attentional resources?
• The Magical Number Seven (plus or minus two).

The bottle can only allow in as much fluid as its
neck allows.
Example of a dam controls the flow of water
downstream.
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Seven Plus or Minus Two
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Check your answers

• three
• four
• five
• six
• seven
• eight
• nine
• ten
• eleven

P X R H G P A Z C M I L K H K S D E V U J A Z I
W G O K Y R X D N S K J E Z F X Y T U N K M I H C
Q P F R U J A Z I W T K F C
Was your memory capacity for letters close to
seven (plus or minus two)?
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Overcoming STM limitations

• Chunking
• Recoding

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Chunking

• The process of reducing complex information into
  smaller parts (chunks) to aid in memory storage
  and retrieval.
• Going from larger to smaller
• e.g. Remembering phone numbers.
• [phone] compared to 7039931207
• Chunks can vary in size from single letters to
  entire words
• BYGROUPINGSIMILARITEMSINTOUNITSWEREMMBERTHEMBETTE
  R

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Recoding

• Grouping smaller items together and remembering
  the newly formed groups.
• You recode some items into a different form
• Going from smaller to larger
• Example Remembering items on a grocery list
• Mnemonic devices (next weeks class)

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Addressing the duration of STM storage

• Influences of decay and interference on duration.

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The Brown-Peterson Task (1958)

• Goal Determine how long non-rehearsed
  information stays in STM.
• On each trial, the subject sees three letters,
  followed by three numbers.
• Subjects must remember the letters while counting
  backward by 3s from the number.
• Plot recall accuracy by time spent counting.

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Brown-Petersen Example (3 sec)

• M N P, 309

count backwards
What are the three letters?
20
Brown-Petersen Example (9 sec)

• E J H, 306

count backwards
What are the three letters?
21
Recall Accuracy in the Brown-Peterson Task
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Brown-Petersons Interpretation.

• The data represent a simple decay function.
• Decay Loss of a memory trace due simply to the
  passage of time.
• Assumed no interference due to difference between
  letters and numbers

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Challenge to decay only explanation in STM

• Interference (loss of a memory trace due to
  competition from other events) plays little or no
  part in this task.
• Waugh and Norman (1965)
• Subjects heard a list of digits read at either 1
  or 4 digits per second. (total time span in both
  cases is 4 seconds)
• Last digit was a repeat of an earlier one.
  Subject had to remember which digit came after it
  in the list.
• Example 7, 4, 6, 9.4 last digit is 4, recall
  the digit 6.

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Waugh and Normans Task
8
1
5
7
1
Recall
Time (always 4 seconds)
25
Waugh and Normans Task
6
2
8
1
2
26
Waugh and Normans Task
3
5
6
8
7
6
4
2
8
9
2
1
7
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Waugh and Normans Results

• Recall was better when fewer digits were
  presented in the 4 second time span.

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Interference or Decay?

• How do Waugh and Normans results demonstrate
  that interference rather than decay is the loss
  mechanism in STM?
• Other evidence for interference (Keppel and
  Underwood, 1962)
• Performance on the Brown-Peterson Task is
  relatively good early on (and nearly perfect on
  Trial 1).
• Performance gets much worse on later trials.
• Proactive interference of previous information

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Proactive Interference

• Previous information interferes with new learning
  
• example. Today, I walk to where I parked my car
  yesterday.

Present Information
Previous Information
Time
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Retroactive Interference

• More recent information interferes with older
  learning. (interruptions)
• Example. I hear a busy signal when calling
  someone and it interferes with the memory of the
  phone number I called.

Present Information
Previous Information
Time
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Release from Proactive Interference

• When the stimuli are switched in the
  Brown-Peterson task, proactive interference goes
  away.
• Wickens (1972)

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Brown-PetersenTask
PI ReleaseVariation

• M N P, 309
• Y P O, 316
• I K N , 218
• Q X P, 870
• etc

• M N P, 309
• Y P O, 316
• I K N , 218
• 4 5 8 , 870
• etc

Accuracy gets worse in later trials (proactive
Interference)
On the 4th trial letters switched to numbers
Recall accuracy on the 4th trial matched
accuracy on the 1st trial
33
Why do we rehearse information?

• Keeps information in STM.
• Increases probability information will be
  transferred to long-term memory.

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How do we retrieve the contents of memory?

• Recall
• Recognition

35
Short-Term Memory Recall

• Free recall recall the items in any order
• Exact order of list not necessarily important
• Example, a grocery list
• Serial recall recall the items in exact order of
  presentation
• Order is important
• Example, a phone number

36
Effects of item order on serial recall

• Primacy Better memory for the first items in a
  list.
• Recency Better memory for the last items in a
  list.
• Imagine a 5 year old reciting the alphabet.

37
Explanations of Serial Order Effects

• Primacy
• First items get the most rehearsal.
• A long-term memory effect.
• Recency
• Last items still in STM at time of recall.
• A short-term memory effect.
• Middle items
• Not as much time for rehearsal
• Already decayed from STM at time of recall.

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Recognition
Study Phase

• Remember this face

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Recognition
Test Phase
Test Phase

• Did you see any of these faces earlier?

• What are some other real life examples of
  recognition?

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How do we search the contents of STM?

• Sternbergs (1966) STM Scanning Task
• On each trial, subjects saw a memory set,
  consisting of between 2 and 5 numbers.
• After the memory set disappeared, a single, probe
  digit appeared.
• Yes or No, was the probe digit a member of the
  memory set?

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Sample Sternberg Task
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Process Model of the Sternberg Task
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How Might People Scan STM?

• Parallel Search (e.g., yes, or no, are my car
  keys on the table?).
• Serial Self Terminating Search (e.g., my keys
  could be on the sofa, the kitchen table, or in
  the car. I find them on the sofa, and stop my
  search).
• Serial Exhaustive (e.g., a police line up).

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Sternbergs Results
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Summary of Sternberg

• People scan STM in a serial exhaustive fashion
  (dont stop even if a match is found).
• The scan rate is about 38 msec per item
  (Sternbergs slope).
• The intercept represents the time it takes for
  all other stages in Sternbergs model.

46
Working Memory
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Working Memory(Baddeley, 1974)

• Executive and two slave systems.
• All share resources.

Baddeley, A., and Hitch, G., Working Memory, in
Bower, G.H. (Ed.), The Psychology of Learning and
Motivation, Vol. 8. New York, Academic Press,
1974, pp. 4789. Adapted by permission of the
publisher.
48
Components of Working Memory

• Central Executive
• Planning future actions
• Initiating retrieval and decision processes
• Integrating information coming into the system.
• Transfer information to long term memory via
  rehearsal

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Components of Working Memory

• Visuo-Spatial Sketch Pad
• Visual and spatial information
• e.g. visual, spatial search
• Example Is the doorknob for your bedroom door on
  the left or right side?
• Drains executives resources if visual task is
  demanding.

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Components of Working Memory

• Phonological Loop
• Rehearsal of verbal information
• Phonological (auditory) processing
• Drains executives resources if verbal task is
  demanding.

51
Measuring Working Memory Capacity- Individual
Differences

• Memory Span Tasks (dual-task methods)
• Reading-Span
• Subjects must process the sentences and words
• some sentences WORD1
• more sentences WORD2
• Arithmetic Operations-Span
• Subjects must process the arithmetic problems and
  words
• Is (6 x 2) - 2 10? WORD1
• Is (3 x 4) - 4 9? WORD2
• Subjects are scored on
• ability to process the sentences and arithmetic
  problems.
• the of words they can recall.

52
Measuring Working Memory Capacity- Individual
Differences

• People classified into low and high WM spans
  based upon scores.
• Performance on these tasks correlate strongly
  with higherorder tasks. Also correlate with
  aptitude and achievement tests.

53
An alternative approach toworking memory
(Engle, 2002)

• Working memory not directly about memory
• Focus less on subjects accuracy for word recall
  in dual task procedures (which measures memory
  capacity).
• Contrasts with general approaches to STM.
• Working memory more about directing attention and
  avoiding proactive interference.
• Actively maintaining a task goal is important for
  performance
• Proactive interference causes task goals to be
  forgotten and performance suffers

54
Experiments to support alternative approach to
working memory

• Antisaccade Task
• Shadowing Task

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Antisaccade task
This is the fixation point


This is the target cue It always appears on the
opposite side of the target And predicts where
it will be!
This is the target
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Antisaccade Results

• Low WM spans slower reaction times in finding
  the target
• High WM spans faster reaction times in finding
  the target

57
What does having a low ability to recall words in
the memory span tasks have to do with remembering
that the target cues predict the target location
in the antisaccade task?

• In both tasks, the maintenance of the task goals
  requires work.
• People with high WM able to reduce effects of
  interference and focus on task
• People with low WM memory more easily distracted
  by interference

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Further support for alternative view of working
memory

• In the shadowing task
• Subjects with low WM span will detect their name
  in unattended ear.
• Subjects with high WM span will detect their name
  less often.

Shadowing Task

• Again, WM associated with ones ability to direct
  attention and focus on task goal while reducing
  interference.

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Short Term, Working Memory- Lecture Outline

• Short Term Memory (STM)
• Short term memory limitations
• Limited capacity bottleneck
• Overcoming the bottleneck
• Duration
• Decay
• The Brown Peterson task
• Interference
• Accessing contents of memory
• Recall
• Free versus serial recall
• Serial position effects
• Recognition
• Searching the contents of STM
• Serial exhaustive search
• Sternberg
• Working Memory (WM)
• The components of working memory (Baddely)