Visual Attention Visual Attention • Attention is the ability to select objects of interest from the surrounding environment • A reliable measure of attention is eye movement during object (target) selection • Early studies show that there are specific brain regions that are involved in the process of target selection
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Visual Attention Attention is the ability to select objects of interest from the surrounding environment A reliable measure of attention is eye movement.
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Visual AttentionVisual Attention
• Attention is the ability to select objects of interest from the
surrounding environment
• A reliable measure of attention is eye movement during
object (target) selection
• Early studies show that there are specific brain regions that
are involved in the process of target selection
Visual AttentionVisual Attention
• Attention is the ability to select objects of interest from the
surrounding environment
• A reliable measure of attention is eye movement during
object (target) selection
• Early studies show that there are specific brain regions that
are involved in the process of target selection
– Superior Colliculus
Visual AttentionVisual Attention
• Attention is the ability to select objects of interest from the
surrounding environment
• A reliable measure of attention is eye movement during
object (target) selection
• Early studies show that there are specific brain regions that
are involved in the process of target selection
– Superior Colliculus
– Frontal Eye Field
Visual AttentionVisual Attention
• Attention is the ability to select objects of interest from the
surrounding environment
• A reliable measure of attention is eye movement during
object (target) selection
• Early studies show that there are specific brain regions that
are involved in the process of target selection
– Superior Colliculus
– Frontal Eye Field
– Extrastriate Areas (V1, V4, IT)
Superior Colliculus & Target Superior Colliculus & Target Selection: Early StudiesSelection: Early Studies
• Cells in the superficial layers of the SC respond to light
falling on a specific area of the retina
• Visual response occurs 50ms after stimulus onset even
when the stimulus appears in the RF and the monkey
maintains fixation
Superior Colliculus & Target Superior Colliculus & Target Selection: Early StudiesSelection: Early Studies
• Enhanced visual response when the stimulus appears in the
cell’s receptive field AND the monkey selects it as a target
and saccades (overtly attends) to it. Latency of saccade is
about 200ms
• Activity is greater for target + saccade than for target
Superior Colliculus & Target Superior Colliculus & Target Selection: Early StudiesSelection: Early Studies
• No enhanced response when the monkey saccades to a
stimulus outside the receptive field (or in total darkness)
Superior Colliculus & Target Superior Colliculus & Target Selection: Early StudiesSelection: Early Studies
• No enhanced response when the monkey covertly attends
to the stimulus in the receptive field
• At least this is what they found back then
Conclusions from Early StudiesConclusions from Early Studies
• Early studies suggest that the superior colliculus is involved
in the selection of targets for eye movements
– Not just a visual response to stimulus
– Not just a motor response to saccade
• Greatest level of activity is found when both a target is
presented and a subsequent saccade is made to that target
Target Selection and UncertaintyTarget Selection and Uncertainty
• Behavioral Task – Uncertainty period: array of
possible targets presented
– Selection period: one of the
targets is dimmed
– Removal of fixation signaled
saccade initiation
• Manipulated uncertainty by
varying the # of possible
targets (distractors)
• Recorded activity in SC
intermediate layer neurons
Visual Response Modulated by Visual Response Modulated by Uncertainty / # of DistractorsUncertainty / # of Distractors
• Response during stimulus
onset in the uncertainty
period decreases as the #
of distractors (uncertainty
level) increases
• Response during selection
and saccade initiation were
not significantly different
regardless of uncertainty
The Frontal Eye Field & Target The Frontal Eye Field & Target SelectionSelection
• FEF cells respond to visual stimuli like the SC
– Greater activity for spots of light in the receptive field
– RF is larger: as big as a ¼ of an entire visual field
Decreased Activity with Increased Decreased Activity with Increased Uncertainty / # of DistractorsUncertainty / # of Distractors