Crosstask Prediction of Working Memory Performance: Working Memory Capacity as Source Activation - PowerPoint PPT Presentation
1 / 18
Title:
Crosstask Prediction of Working Memory Performance: Working Memory Capacity as Source Activation
Description:
New Work: The n-back task. Subjects view a long sequence of letters ... 2-back - letter is a target if it matches the letter before the previous one ... – PowerPoint PPT presentation
Number of Views:85
Avg rating:3.0/5.0
Title: Crosstask Prediction of Working Memory Performance: Working Memory Capacity as Source Activation
1
Cross-task Prediction of Working Memory
PerformanceWorking Memory Capacity as Source
Activation
- Larry Z. Daily, Marsha C. Lovett, and Lynne M.
Reder - Carnegie Mellon University
- Thanks to Scott Filipino for assistance in
collecting the data. - This work supported grant F49620-97-1-0455 from
the Air Force Office of Scientific Research and
grant N00014-95-1-0223 from the Office of Naval
Research.
2
Working Memory in ACT-R
- Provides the resources needed to retrieve and
maintain information during cognitive processing
(Baddeley, 1986)
- Working memory capacity is limited
- W is limited (Anderson, Reder, Lebiere, 1996)
- Working memory limits vary across individuals
- W varies over individuals (Lovett, Reder,
Lebiere, 1999)
3
Prior WorkThe MODS Task
- MOdified Digit Span
- Read strings of digits and letters aloud
- Remember the numbers
- Memory set size varied from 3 to 6
4
MODS TaskAggregate Results
5
MODS TaskIndividual Accuracy
6
MODS TaskIndividual Serial Position
7
CAM InductiveReasoning Subtest
8
Cross-task Correlations
- Estimates of W strongly correlated with scores on
CAM inductive reasoning subtest - r 0.50 r2 .25
- Correlations are a weak test of Ws predictive
ability - No model of the CAM
9
New WorkThe n-back task
- Subjects view a long sequence of letters
- For each, indicate whether it is a target or
non-target - Targets defined by condition
- 0-back - target is a letter given at the start
- 1-back - letter is a target if it matches the
previous letter - 2-back - letter is a target if it matches the
letter before the previous one - 3-back - letter is a target if it matches the
letter 3 before the current one
10
N-back Strategies
- Familiarity-based
- Subjects use familiarity to decide whether an
item is a target - Doesnt depend on W
- Update
- Subjects actively try to maintain a list of prior
items - Does depend on W
- We model this
11
The n-back Model
- Encodes the item currently in vision
- Memory chunk encodes item and position
- Attempts to match the item to a stored memory
- Looks for a memory chunk with a position that
matches the n-back condition and the correct item - Sets a flag to indicate match or not
12
The n-back Model
- Responds
- Target or non-target based on flag
- Updates memory chunks
- Changes the position of each chunk up through the
current n-back condition - If this process fails, several responses required
to get back on track
13
Aggregate Results
14
Individual ResultsMODS Task
15
Individual ResultsMODS Task
16
Individual ResultsN-back Task
17
Individual ResultsN-back Task
18
Conclusions
- Varying W captures differences in individuals
working memory performance. - W can be used to predict performance across
tasks. - W is a workable measure of working memory
capacity. - ACT-R can be fruitfully applied to the study of
individual differences.
Recommended
CrystalGraphics Presentations
