Visual Attention

Question 1

How are neural representations modulated?

Answer 1

Through top-down and bottom-up interactions

Question 2

What kind of attention is involved in filtering background noise to effectively focus on one conversation (cocktail party effect)?

Answer 2

Selective attention

Question 3

What is ‘visual search’?

Answer 3

Actively search for specific environmental features

Question 4

What is a simple way to study selective attention & visual search?

Answer 4

Eye tracking

Question 5

What is covert attention?

Answer 5

Visual spatial attention: Fixed gaze at fixation point with direct attention on other location

Question 6

What does covert attention allow us to do?

Answer 6

To inhibit ‘things’ effectively

Question 7

Describe the spatial orienting task shortly.
What kind of attention does it study?

Answer 7

Selective attention:
There is valid cue trial in which the visual cue (pijltje) points at the detection stim.
There is also an invalid cue trial in which the detection stim is on the opposite side on which the visual cue points to.
RT in both situation are compared.

Question 8

What was seen in the results of Posners experiment when cue delays were manipulated?

Answer 8

Cueing first shows a facilitatory affect, but after a certain period of time, the RT of valid cueing was a lot slower response to the cued location. While uncued RT stayed reduced but at the beginning had a slower RT than valid cues
–> Cueing causes a inhibitory effect

Question 9

What happens when the delay between cue and target becomes to large?

Answer 9

Attention moves away from location (disenganged), further processing in that location is temporarily inhibited which slows down the response to a target that appears later on.

Question 10

How is it called when a facilitatory effect changes into inhibitory effect, causing the research object to avoid the region of space?

Answer 10

Inhibition of Return

Question 11

What are the differences between a central and peripheral cue?

Answer 11

Central cue: Endogenous attention, voluntary/chosen, top-down attention (slow)
Peripheral cue: exogenous attention, stimulus driven, bottom-up attention (fast), inhibition of return

Question 12

What was concluded from Posners Spatial cueing task?

Answer 12

Attentional focus is not tied to eye movements or other overt behavior but to an internal focusing mechanism

Question 13

In a visual search task, how are simple and complex features possibly processed?

Answer 13

Simple features may be excracted pre-attentively but features from more complex scenes involve a top-down mechanism of visual search

Question 14

What kind of aspects are automatic visual processing according to Traisman’s Feature Integration Theory?

Answer 14

Search of specific features like color or shape.
Features that are processed in seperate brain areas.

Question 15

In what kind of aspects is serial processing involved according to Traisman’s Feature Integration Theory?

Answer 15

In situations where all locations need to be examined. Searching for conjunctions, so combinations of features.

Question 16

What is the binding problem?

Answer 16

The fact that aspects of a ‘unit’ that u see are detected by different system which all have to be connected to each other to fully identify the ‘unit’. –> communication between different areas

Question 17

What is the difference between the Gelade & Treisman model and the Posners model?

Answer 17

G&T: Look at object with a preattentive stage where the object is being analyzed to later on in the focused attention stage to combine the features to look at perception –> attention used to combine

Posners: Look at object in a space where there is a pre-cue stage and after looks at focused attention stage to look at perception

Question 18

What is contrast sensitivity?

Answer 18

The ability to distinguish an object from its background

Question 19

What are the behavioral effects of attention?

Answer 19

• Focused attention speeds RT
• Attention increases contrast sensitivity
• Attention increases spatial resolution

Question 20

What was concluded from the texture segregation task?

Answer 20

• Attention impaired performance at central retinal locations where resolution was high
• Attention increased performance at the periphery where spatial resolution is lowW

Question 21

What is the effect of attention in the visual cortex?

Answer 21

Visual attention mechanism increase the S/N-ratio of the attended features

Question 22

What effect does attention have on the firing rate of V4 neurons?

Answer 22

It increases their firing rate, increasing their contrast sensitivity

Question 23

What is meant with ‘bias competition’?

Answer 23

Attention produces a bias competition of the target stimulus at expenses of the distractors

Question 24

How is competitive selection in visual areas implemented in the brain?

Answer 24

Through synaptic gain of post synaptic population –> Biased competition: higher firing rate for what is biased for.

Question 25

How does attention influence oscillatory activity?

Answer 25

It facilitates the transmission of information in a more efficient way

Question 26

Which areas are mostly consistent activate during attention to stimulus attributes?

Answer 26

• Dorsal parietal cortex
• Superior parietal lobule
• Postcentral sulcus
• Dorsal frontal cortex
• Superior frontal sulci (FEF for eye movement, spotlight of attention)

Question 27

Where is the dorsal-fronto parietal network involved in?

Answer 27

Top-down control of visual attention

Question 28

Which subcortical structure coordinates multiple visual areas during attention and how?

Answer 28

Pulvinar (from thalamus) by increasing synchrony at low-frequencies.

Question 29

Which structure amplifies the cortical connectivity between higher and lower areas, enabeling efficient top-down connectivity?

Answer 29

Thalamic nuclei

Question 30

What is bottom-up control of attention?

Answer 30

Attention grabbed by salient stimuli (stimuli that have high intrinsic value)

Question 31

What is top-down control of attention?

Answer 31

Attention guided by internal values/goals, allowing selectivity to relevance of current task

Question 32

What happens when there is hemineglect?

Answer 32

Cortical lesion:
Contralateral stimuli is ignored/neglected to some degree and cannot be attended to as completely or accurately as normal

Question 33

If someone has Balint’s Syndrome lesions, wheren can these lesion be found?

Answer 33

Posterior parietal and lateral occipital, bilaterally

Question 34

What are the neurological deficits in Balint’s Syndrome?

Answer 34

• Simultanagnosia: Inability to atten to/or perceive more than one visual object at a time
• Optic taxia: Impaired ability to reach for/or point to an object in space under visual guidance
• Oculomotor Apraxia: Difficulty voluntarily directing the eye gaze towards objects in the visual field

Question 35

Where are top-down responses during visual attention originated from?

Answer 35

Frontal and parietal regions