Lecture 13 Attention Flashcards
(28 cards)
What happens when V1 is damaged?
It causes cortical blindness—loss of visual awareness despite intact retinal input.
What visual condition may result from a lesion to V1?
Scotoma; its size depends on the extent of the lesion.
Can unconscious visual processing remain after V1 damage?
Yes, ablation studies show unconscious processing remains.
What is blindsight?
Above-chance visual performance in the ‘blind’ hemifield after V1 damage, without conscious awareness.
What functions may be preserved in blindsight?
- Pupillary reflexes
- manual/saccadic localisation
- wavelength/motion/orientation/shape discrimination.
Which pathways support blindsight?
Older visual pathways: superior colliculus and pulvinar nucleus.
上丘和枕核
Why doesn’t blindsight support spontaneous visual behaviour?
Because individuals won’t orient to changes unless prompted.
What is change blindness?
Failure to notice changes in a visual scene due to
attentional masking(dramatic change in environment that capturing attention).
What does change blindness reveal about attention?
Attention regulates our conscious visual awareness.
What does blindsight tell us about visual consciousness?
Visual processing can occur without conscious awareness.
What limits our visual awareness?
- Neural bottlenecks
- metabolic cost
- computational complexity/efficiency
- Conscious decision making
Why are we only aware of a small part of the visual world?
To reduce neural load, save energy, and focus on important stimuli.
What are the components of attention?
- Selectivity (Spatial, temporal, motoric)
- capacity limitation
- vigilance
- perceptual set
- switching
How is attention defined in experiments?
1) increased sensitivity at attended locations
2) **faster reaction **times.
What effect does spatial attention have on neural processing?
It increases processing speed and responsiveness to stimuli.
What have monkey studies shown about parietal neurons and attention?
Neurons fire more when attention is directed to a stimulus.
What do these monkey findings explain about neglect in humans?
Damage to parietal neurons may cause attention loss to one side of visual field.
How does attention affect neurons in V2/V4?
Increases spatial selectivity,
especially when multiple stimuli are in the receptive field.
- Effect of attention is greatest for two stimuli in RF
What did Watanabe et al. find using fMRI?
Attention to motion types increased fMRI signals in V1 and MT/MST.
What is the role of attention in early/mid-level visual areas?
Attention modulates activity based on
motion type and task demands.
Which brain areas show neural correlates of visual attention?
-
Sub cortical regions:
Superior colliculus, pulvinar nucleus, -
Visual responsive cortical regions:
IPS 顶内沟, AIP, LIP, VIP, CIP, MIP, V1–V4, MT/MST - prefrontal cortex.
What is unilateral spatial neglect?
A condition where patients ignore the contralesional side of space, often after right parietal damage.
What are some signs of spatial neglect?
Ignoring food on one side, bumping into objects, not grooming one side, missing text.
What is representational neglect?
- Neglect in the absence of visual input
- Often in conjunction with regular neglect
