Download 11 Attention

11 Attention
Psychology 355
Introduction
I.
Attention: State of selectively processing
simultaneous sources of information
II. Benefits: Performance of behavioral tasks
III. Brain Imaging – changes in cortical activity
IV. Behavioral manifestations
Visual attention; Auditory attention
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Introduction
Functions of attention
A.
Concentrate on one object in visual field
B.
Selectively attend to information (while
ignoring other information)
C.
Preferential processing of sensory
information
Attention-deficit hyperactivity disorder
Demonstrates critical nature of intact
attentional mechanisms
Brain imaging studies
Show that cortical activity is altered by
attention
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Behavioral Attention
Visual attention
A. Move eyes until object imaged on fovea
B. Shifting attention
C. Enhanced visual processing
1) Enhanced detection
2) Faster reaction times
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Behavioral
Attention
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->
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Behavioral
Attention
Faster Reaction Times
Enhanced Detection
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Behavioral Attention
Neglect Syndrome as an Attentional Disorder
Person ignores objects, people, and their
own body to one side of the center of
the gaze
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Physiological Attention
Shifting attention
A. What happens to neural activity?
B. What brain areas are involved?
Observed in high-level cognitive and
numerous sensory areas
e.g., Area V1 to visual cortical areas
in the parietal and temporal lobes
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Physiological
Attention
I.
Functional MRI
Imaging of
Attention to
Location
A. Subjects view
stimulus
B. Change
location of
attended
sector
C. Brain activity
shifts
retinotopicallyPsychology 355
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Physiological
Attention
PET Imaging of Attention to
Features
A.
Same-different
discrimination task
1.
Features: Color,
shape, speed
2.
(A) Selective
attention: one feature
3.
(B) Divided attention:
all features
4.
Subtract B from A
shows brain activity
associated with
attention to one
feature
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Physiological
Attention
PET Imaging
Attention to
Features
Speed
Color
Shape
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Physiological
Attention
Enhanced Neuronal Responses in Parietal Cortex
A. Attention: Experimental vs. Normal
conditions
B. What happens to attention under normal
conditions?
C. Test the Hypothesis:
Attention changes location prior to eye
movement
D. Wurtz, Goldberg, and Robinson: Record
neural activity from Posterior Parietal
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Physiological
Attention
Enhanced Neuronal
Responses in Parietal
Cortex
A Posterior parietal cortex
neurons
B Directing eye movements
C Response significantly
enhanced neuronal
response when eyes
went to target
Its either an attention
shift or a
premotor signal
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Physiological Attention
Receptive Field Changes in Area V4
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How is Attention Directed?
I.
Cortical, subcortical areas
A.
Modulate the activity of neurons in sensory
cortex areas
II. The Pulvinar Nucleus
A.
In humans: Damage
to the PN results in
slow responses
to stimuli on the
contralateral side
B.
Muscimol (GABA agonist;
suppresses activity) in
monkey PN results in
impairment of attention
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shifting
How is Attention Directed?
I.
Attention and Eye Movements
A. Eye moves to attended object
B. Eye movements & attention closely
related
C. Recent experiments
1. Brain circuitry: Directing eyes to
objects of interest
D. Frontal Eye Fields (FEF)
1. Cortical area
2. FEF neurons
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How is Attention Directed?
Attention and Eye Movements (Cont’d)
Experiment
1.
Train monkeys to look at
display of small light spots
2.
Place electrode in FEF and
determine motor field of
neurons at the tip
3.
Small electrical stimulation
enhancement?
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How is Attention Directed?
Attention and Eye Movements (Cont’d)
Results
FEF involved in directing
attention; Enhancing
visual performance
Conclusion
Guidance of attention
Integrated
with system
to move eyes
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Concluding Remarks
I.
Studies of attention
A. Point to flexibility of the human brain
II. More mental energy to one location
A. Enhanced sensitivity & reaction time
B. Ignoring competing stimuli
III. Need for attention
A. e.g.,- Cannot process ALL information in
area V1
B. Selects what information should access
the limited processing resources
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End of Presentation
Psychology 355