Task 5

Question 1

Watanabe Experiment

Answer 1

Researchers separately examined the effects of top-down attention and visual awareness on the BOLD signal in the human V1

Two-by-two factorial design:
- visibility of the target stimulus (visible or invisible)
- directed attention (target or nontarget location)

Question 2

Watanabe Experiment: Findings

Answer 2

When multiple patches of smaller motion gratings (Dynamic Mondrians) were shown to the opposite eye as that of the perceptual target, the target was rendered invisible because of binocular suppression

–> when they were shown to the eye of the perceptual target, the target remained visibile

Question 3

Attention vs. Awareness (Watanabe)

Answer 3

• attention but not awareness modulates the BOLD signal in the human V1 during binocular suppression
• the BOLD response was unaffected by whether the participant lying in a scanner saw the target or not
• visual awareness and visual attention are two dissociated functions in the visual system
• supported by distinct neuronal mechanisms

Question 4

Attention and Consciousness

Answer 4

• attention and consciousness are related yet different
• one can attend to an object without becoming aware (conscious) of it

Question 5

Hypothesis by Crick and Koch

Answer 5

V1 neurons do not directly contribute to visual awareness

• it may be that consciousness (awareness) does modulate neuronal response in V1 during continuous binocular rivalry (suppression) but not at the onset of rivalry induced by a short-duration stimulus

Question 6

Lamme: Why visual attention and awareness are different

Answer 6

Selectiveness –> we are not aware of everything we lay our eyes on

Neuroscience –> there is neural activity that produces conscious experience and neural activity that does not

–> we are aware of what is in the focus of attention

Question 7

Awareness and Attentive Selection

Answer 7

• change blindness and inattentional blindness hint at selective processes
• even though we think we see everything that is in front of us, we actually have a very limited conscious representation of the outside world

–> many sensory inputs reach the brain and, via the process of attentive selection, some of these reach a conscious state, which allows us to report about them

Question 8

Classes/Levels of Selection

Answer 8

Unconscious, unattended, and attended

Option 1: only attended stimuli reach awareness

Option 2: there is no difference between attended and conscious stimuli

Question 9

Separating Awareness from Attention

Answer 9

Attention does not determine whether stimuli reach a conscious state but determines whether a conscious report about stimuli is possible

–> attention determines whether items are stored in a sufficiently stable manner (working memory)
–> we are conscious of many inputs but, without attention, this conscious experience cannot be reported and is quickly erased and forgotten

Question 10

External (Exogenous) Attention

Answer 10

• salient stimuli are processed more efficiently than others
• saliency reflect how long-term memory shapes and modifies sensory processing
• something “grabs” your attention

Question 11

Attentional Priming

Answer 11

• the processing of a stimulus will leave a trace of activated and inhibited neurons that can last for a variable amount of time

–> the processing of subsequent stimuli might benefit from this trace if the two stimuli share properties, resulting in attentional priming

Question 12

Endogenous Attention

Answer 12

• you direct your attention
• parts of the brain that extract the meaning of the cue, and that are able to relate this to current needs and goals, must preactivate or otherwise facilitate the appropriate sensory pathways

Question 13

Feedforward Connections

Answer 13

Feedforward connections are capable of generating sophisticated receptive field (RF) tuning properties and thus extracting high-level information, which could lead to categorization and selective behavioral responses

Question 14

Feedforward Sweep (FFS)

Answer 14

= the earliest activation of cells in successive areas of the cortical hierarchy

• as soon as the FFS has reached an area, recurrent interactions between neurons within that area and neurons that have been activated at earlier lower levels can start

–> visual processing mediated by the FFS is not accompanied by awareness

Question 15

Backward Masking

Answer 15

Renders a visual stimulus invisible by presenting a second stimulus shortly after the first

–> the masked stimulus, although invisible, still evokes selective feedforward activation in the visual and non-visual areas

–> neurophysiological manifestations of recurrent interactions are suppressed by backward masking

Question 16

Recurrent Processing (RP)

Answer 16

Conscious visual experience (awareness) requires recurrent processing of interactions between visual and higher areas

Question 17

Phenomenal Awareness

Answer 17

Perceptual Awareness arises when:
- early visual areas have started to engage in recurrent interactions
- visual features are related to each other, binding and segregation can occur, and perceptual organization evolves
- at low/early levels there is relatively little competition between stimuli, so groups of recurrent interactions representing multiple stimuli are possible

–> unattended process
–> we can have phenomenal awareness of many items in a scene
–> shares neural mechanisms with iconic (sensory) memory

Question 18

Access Awareness

Answer 18

Access Awareness arises when…
… these recurrent interactions grow more and more widespread and eventually the visual information is put into the context of the systems’ current needs, goals, and full history

–> attended process
–> only a limited number of recurrent groups can span the range from visual to more frontal areas
–> shares neural mechanisms with woking memory