role of working memory in visual selective attention de fockert, rees, frith, lavie (2001)
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Role of Working Role of Working Memory in Visual Memory in Visual
Selective AttentionSelective Attention
de Fockert, Rees, Frith, Lavie (2001)
OutlineOutline
• Definition of Selective Attention• Definition of Working Memory• Previous research• Current research
– Methodology & Results•Behavioural Task• Imaging Study
• Discussion
Selective AttentionSelective Attention
• A system that focuses on relevant information by filtering out irrelevant information from the available stimuli
• The purpose is to reduce the load on cognitive processing systems
Downing, 2000
Working MemoryWorking Memory
• A system used for short-term storage & “executive processes”
Smith & Jonides, 1999
Short-term MemoryShort-term Memory
• Performing active maintenance of a limited amount of information for a matter of seconds
Smith & Jonides, 1999
Executive ProcessesExecutive Processes
• Attention & Inhibition (Competition)
• Task Management• Planning• Monitoring• Coding
Smith & Jonides, 1999
Low Working Memory Low Working Memory LoadLoad
Attention & Inhibition
Task Management
Coding
Monitoring & Updating
Planning
*adapted from Smith & Jonides, 1999
High Working Memory High Working Memory LoadLoad
Attention & Inhibition
Task Management
Coding
Monitoring & Updating
Planning
Working Memory LoadWorking Memory Load
As working memory load increases, processing of irrelevant stimuli also
increases, and vice versa.
Previous ResearchPrevious Research
• Working memory may provide top-down modulation of selective attention
• Active maintenance of objects in working memory caused selective attention to shift towards that object
Downing, 2001
LeBar et al (1999)LeBar et al (1999)
• Physiological overlap between working memory and visuospatial attention tasks
• Concluded that spatial attention and working memory use common cognitive features
• This would require dynamic shifting of attentional resources
Current PaperCurrent Paper
HypothesisHypothesis
• Selective Attention relies on Working Memory to prioritize stimuli to process relevant stimuli
*BUT if Working Memory is busy than Selective Attention will process irrelevant stimuli to a greater degree
MethodologyMethodology
Behavioural Task
500 ms
500 ms
3000 ms
1500 ms
850 ms
500 ms
1250 ms
Response Interval
1250 ms
Response Interval
Example of Example of High Working High Working Memory Load Memory Load condition with condition with two Selective two Selective Attention Attention tasks.tasks.
PredictionsPredictions
Distractor Faces Low WM Load High WM Load
Congruent No effect No effect
Incongruent No effectIncreased RT and Error
Working Memory Load
ResultsResults
Behavioural Data
ResultsResults
Task Low WM Load High WM Load
Selective Attention Manipulation (Response 1)
739 ms (er=5%)
752 ms (er=5.5%)
Working Memory Manipulation* (Response 2)
214 ms (er=4%)
642 ms (er=8%)
Working Memory Load
*significant main effect
Distractor Effects by Working Memory Load
0
100
200
300
400
500
600
700
800
Low WM Load High WM Load
Working Memory Load
Dis
trac
tor
Effec
ts (
ms)
SelectiveAttentionManipulation
WorkingMemoryManipulation
Distractor Distractor Interference/CongruencInterference/Congruenc
y Effectsy Effects
• Low working memory load = 46 ms (error rate=3%)
• High working memory load = 78 ms (error rate=4%)
• F(1,9) = 13.36, P<0.01
MethodologyMethodology
Imaging Task
PredictionsPredictions
Selective Attention Task Low WM Load High WM Load
No distractor facesNo distractor processing
No distractor processing
Distractor faces present & incongruent
No distractor processing
High distractor processing
Working Memory Load
DetailsDetails
• 6 participants (4 males, 2 females)
• 2T Siemens VISION system measured BOLD signal
• 32 contiguous 3-mm axial slices per volume
• Acquired every 2800 ms• Total of 720 volumes acquired in
six runs
Epoch SequenceEpoch Sequence
Low WM load and face incongruent
High WM load and face incongruent
Low WM load and face absent
High WM load and face absent
Run1
Run2
Run3
Run4
Run5
Run6
5 memory trials and 15 attention displays
} Block Design
Results Results
Imaging Data
Significant Significant activations activations related to related to Working Working
Memory Load- Memory Load- LHLH
Superior temporal gyrus
Precentral gyrus
Inferior frontal gyrus
Significant Significant activations activations related to related to Working Working
Memory Load- Memory Load- RHRH
Precentral gyrus
Superior temporal gyrus
Superior parietal lobe
Significant activations related to Significant activations related to the interaction between the interaction between
selective attention and working selective attention and working memory load include:memory load include:
• Bilateral fusiform gyri• Right inferior occipital lobe• Left lingual gyrus
Significant Significant activations related to activations related to
the interactionthe interaction
Occipitotemporal gyrus (Fusiform gyrus) (bilateral)
Lingual gyrus (left)
Occipital Lobe (right)
Low WM
High WM
Percent signal change for face Percent signal change for face presence versus absencepresence versus absence
• Graph represents the maxima of interaction in right fusiform gyrus, separated by working memory load
DiscussionDiscussion
• It is concluded that working memory and the prefrontal cortex plays an important role in controlling selective attention
The EndThe End
Perceptual vs Working Perceptual vs Working Memory LoadMemory Load
Perceptual LoadAs perceptual load increases, processing of irrelevant stimuli decreases, and vice versa.
Previous WorkPrevious Work
• Physiological overlap between areas involved in working memory and interference resolution (Binge et al, 2001)
Analysis using SPMAnalysis using SPM
• Voxel-based• Images are spatially
normalised into standard space and smoothed
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