psychology 355 11 attention. psychology 3552 introduction i.attention: state of selectively...
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Psychology 355
11 Attention
Psychology 355 2
Introduction
I. Attention: State of selectively processing simultaneous sources of information
II. Benefits: Performance of behavioral tasksIII. Brain Imaging – changes in cortical activityIV. Behavioral manifestations
Visual attention; Auditory attention
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Introduction
Functions of attentionA. Concentrate on one object in visual fieldB. 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 attentionA. Move eyes until object imaged on foveaB. Shifting attentionC. Enhanced visual processing
1) Enhanced detection2) Faster reaction times
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Behavioral Attention
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Behavioral Attention
Faster Reaction Times
Enhanced Detection
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Behavioral Attention
Neglect Syndrome as an Attentional DisorderPerson ignores objects, people, and their own
body to one side of the center of the gaze
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Physiological Attention
Shifting attentionA. What happens to neural activity?B. What brain areas are involved?
Observed in high-level cognitive and numerous sensory arease.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 retinotopically
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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 CortexA. Attention: Experimental vs. Normal
conditionsB. 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 NeuronalResponses in Parietal Cortex A Posterior parietal cortex
neuronsB Directing eye
movementsC 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 areasA. Modulate the activity of neurons in sensory cortex
areasII. 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) inmonkey PN results in impairment of attention shifting
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How is Attention Directed?
I. Attention and Eye MovementsA. Eye moves to attended objectB. Eye movements & attention closely
relatedC. Recent experiments
1. Brain circuitry: Directing eyes to objects of interest
D. Frontal Eye Fields (FEF)1. Cortical area2. FEF neurons
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How is Attention Directed? Attention and Eye Movements (Cont’d)
Experiment1. Train monkeys to look at
display of small light spots2. 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
ConclusionGuidance of attention
Integrated with system to move eyes
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Concluding Remarks
I. Studies of attentionA. Point to flexibility of the human brain
II. More mental energy to one locationA. Enhanced sensitivity & reaction timeB. Ignoring competing stimuli
III. Need for attentionA. e.g.,- Cannot process ALL information in
area V1B. Selects what information should access
the limited processing resources
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End of Presentation