Task 5 (Attention vs. Consciousness) Flashcards
Attention
Conscious experience is selective - we aren’t aware of everything we perceive
Attention: some sensory inputs are processed faster & deeper than others
- crucial for awareness but yet distinct things
- attention guards way to consciousness
- number of items that survive change blindness correlate with number of items that can be stored in WM, which depends on attention
Lamme: theory 1 of the process of consciousness
Theory 1: when many sensory inputs reach the brain, attention plays a crucial role in this selective process, allowing only some of the inputs to reach a conscious state. Once something has reached a conscious state, it is possible to generate a report of it.
Attention –> Conscious –> Conscious report
Unattended
Lamme: theory 2 of the process of consciousness
Theory 2 suggests the same as theory A, but with the addition of unconscious processing. We can therefore have 3 levels of processing for a visual input: (1) unconscious, (2) unattended, (3) attended.
- this is suggested because we there are many properties that never reach consciousness independent of awareness
Attended –> Conscious –> conscious report
Unattended
unconscious
Lamme: theory 3 of the process of consciousness
Theory A and B suggest that there is no difference between attended and conscious stimuli and therefore some researchers have argued that they are identical. Theory C eliminates the word conscious, equating it to attention, and relies solely on the latter.
Attention –> conscious report
Lamme: theory 4
Theory 4 proposes that attention does not determine whether stimuli reach a conscious state, but rather determines whether (1) a conscious report about stimuli is possible, (2) items are stored in a sufficiently stable manner (in WM) to allow report at a later time or comparison with subsequent scene.
Conscious and unconscious inputs are distinguished earlier in the process.
- model allows for a short-lived and vulnerable form of visual experience which is not easily reportable (conscious, but unattended).
Conscious –> attended –> conscious report
—> unattended
Unconscious
- change blindness and inattention blink are failures of conscious memory, not of consciousness
- iconic memory –> perceptive memory only
Support for Lamme’s theory 4
Cueing an item that might change in a display of many objects protect from change blindness, BUT cueing the item long after the first stimulus has disappears but before the onset of the 2nd stimulus also protects from change blindness
- after the 1st display, a neuronal representation of almost whole scene is still present & attention can select from this to store relevant items
- a short-lived, not easily reportable form of visual experience exist
- attentional selection is independent of awareness and memory but determines whether we go from phenomenal to access awareness
Attention (definition) - neuroscientific perspective
Attention includes increased selective neuronal activity, making processing better, faster and deeper
- increased activity in parietal and frontal regions
Exogenous attention - what makes something salient?
Salient stimuli are processed more efficiently.
Processed stimuli will leave a trace of activated/inhibited neurons that will last for some time
- processing new stimuli may benefit from that trace if stimuli share properties
- trace may change over time
Endogenous attention (neuroscientific perspective)
Part of the brain extract meaning of cues and relate it to current goals. These parts proactive/facilitate the appropriate sensory pathways, mostly via corticocortical feedback or subcortical routes.
Feedforward sweep (FFS)
Earliest activation of cues in successive areas of cortical hierarchy
- V1 starts 40 ms after stimulus onset & higher extrasitrate areas respond at slightly increased latencies
- early responses already fully express receptive field tuning properties of cell
- connections are able to generate sophisticated RF tuning properties & thus extract High-level information which could lead to categorization & selective behavioral responses
ALL THAT HAPPENS UNCONSCIOUSLY
Recurrent processing (RP)
As soon as the feedforward sweep has reached an area, recurrent interaction btw neurons that have been activated earlier at lower levels can start.
- mediated by horizontal connections & feedback-feedforward circuits
ALL THAT GIVES RISE TO CONSCIOUSNESS
How does something become conscious? (Neuro perspective)
- process explained
- supporting evidence
- If multiple stimuli are present, these are present at early stages of FFS
- At higher stages, receptive fields become larger, so that competition starts to arise
- Attentional selection resolves this, so a few stimuli reach the highest level
AT THE SAME TIME: early visual areas have started to engage in recurrent interaction
- visual features are bounded and segregated, so perceptual organization evolves
- synchronous firing
- PHENOMENAL CONSCIOUSNESS
- some of these interactions become more widespread, reaching higher-level executive planning regions: visual info is put into context with current goals & reaches access awareness (stored in WM)
Supporting evidence:
- backward masking evokes FFS but recurrent interaction is suppressed (no access)
- TMS over motion selective area MT introduces motion sensation unless V1 activity is disrupted at a later moment. MT= higher stage, so feedback from MT–> V1 is needed for awareness of motion
- Anesthetized animals still have FFS but not RP
- Figure-ground detection task: when seen RP, when not FFS
Watanabe study
- hypothesis
Visual attention and awareness are distinct: the different effects of top-down attention and visual awareness on BOLD signal in V1 was examined.
Watanabe study - stimuli & procedure
a) target stimulus - grating
l. visible ll. invisible
b) directed attention
l. attention to target: person was asked to report visibility of the target (grating)
ll. attention to non-target block: person asked to detect a given character in a rapidly presented series of characters at the center of fixation
- continuous flash-suppression was used to render motion target invisible
To ensure continuous stimulation, motion grating was presented to one eye as the perceptual target while multiple small motion gratings (dynamic Mondrian’s) were presented to
a) opposite eye (ratite invisible due to binocular suppression)
b) same eye (target visible)
Watanabe study: results
Awareness (visibility or invisibility) of a visual target led to non-significant BOLD effects in V1. Meanwhile, directing attention (toward and away from) a visual target had larger and robust BOLD effects in V1. Such a finding dissociates neural correlates of awareness and attention.
- no consistent effect of visibility on BOLD signal
- highly significant effect of attention regardless visibility was found
- attention, not awareness modulates BOLD signal in V1
a) TOP-DOWN ATTENTION: extends to lower levels of visual hierarchy
b) VISUAL AWARENESS: happens at higher levels of hierarchy
