Attention Flashcards
• Overview of attention • Models/types of attention • Neural mechanisms of attention – Spatial attention – Attention to features & objects – Attentional control & awareness • Neglect & other attention disorders
“Intentional Blindness”
&
“Change Blindness”
Seeing is not the same as perceiving
What
is
attention?
(W. James Quote)
“Everyone knows what attention is. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought.
Focalization, concentration of consciousness are of its essence. It implies withdrawal from some things in order to deal effectively with others, and is a condi6on which has a real opposite in the confused, dazed, scatterbrain state.”
-William James, 1890
4 Properties of Attention:
- Limited Capacity
- Selection
- Modulation
- Vigilance
Types/classes
of Attention
• Covert (“mind’s eye”) vs Overt (actual eye)
• External (coming in through senses) vs Internal (already represented in mind)
• Top‐down (voluntary, goal‐driven)
vs Bottom-up (reflexive, stimulus‐driven)
Overt Attention
look at location/ object of interest
Covert Attention
look at one location but pay attention to another
(moving your “mind’s eye”)
– “These experiments demonstrated, so it seems to me, that by a voluntary kind of intention, even without eye movements, and without changes of accommodation, one can concentrate attention on the sensation from a particular part of our peripheral nervous system and at the same time exclude attention from all other parts”
- Helmholtz (1894)
Cocktail
Party
Effect
Covert Auditory Attention – In-class demo
Models
of
Attention
• Problem:
– Limited capacity: We can’t process everything available to our senses
– How do we select what to attend?
- Early vs late selection
- Do we intentionally select things to attend, (goal-driven)? “top‐down.” Or is attention automatically captured, (stimulus‐driven)? “bottom-‐up.” Actually, it’s Both.
Top‐down
- aka Goal‐directed
* aka Voluntary
Bottom‐up
- aka Stimulus‐driven
* aka Reflexive
Early
vs
Late
Selection
• Limited capacity:
we can’t process everything available to our senses; we have to choose
• When does this selection take place?
– Early Selection
Sensory gating mechanism: only selects stimuli even before they make it to perceptual analysis
– Late Selection
Everything is encoded & perceptually processed before selection
• How deeply are unattended stimuli processed?
Brain regions involved in attention
Temporal-Parietal Junction Posterio -Parietal Junction Superior Prefrontal Superior Colliculus Pulvinar of the Thalamus Ventral Prefrontal
Sources & Sites of Attention
Sources:
Which brain regions are involved in controlling attention?
Sites:
Which brain regions show the effects of attention?
Primarily Frontal and parietal
Superior Colliculus
Attention: automatic Orientating
Posner
Cuing
Task
Response times are measured following Valid, Invalid, and Neutral Commands in a spatial cuing task.
Attentional Facilitation
ERP Variant
Spatial Attention
Attentional
Facilitation:
Behavior is better (faster / more accurate)
for validly-cued locations
Enhanced neural response at validly-cued locations
Enhanced neural response at attended locations
*Posner Cuing Task
Spatial
Attention:
TMS
More likely to see a TMS-induced phosphene
in location being attended
Enhanced baseline activity»_space;> Lowered threshold (takes less stimulation to evoke phosphene)
SpaBal AVenBon:
Neurophys
“This neuron likes blue bars. If blue bar appears in attended location, bigger response!”
If spatial attention is cued to a particular location, which of the following is/are true?
• Reaction times are faster at the validly
cued location?
• Reaction times are slower at the invalidly cued
location?
• ERPs are larger for stimuli at the cued location?
• fMRI responses show that activity in visual cortex is greater at the cued loca
?
Covert vs Overt attention:
Which one involves looking directly at the object of interest?
Overt
What did the change blindness and inattensional blindness demos illustrate?
?
Spatial vs Feature Attention:
Behavior
- Attend to spatial location or mo<on direction
- Both spatial & feature attention enhance behavioral performance
- Spatial may act faster
Spatial vs Feature Attention:
ERP
ERPs of spacial attention and color attention are uncoupled
Feature Attention: fMRI
- Dots changed motion direction and/or color
- Attending to motion increases activity in MT
- Attending to color increases activity in V4
Visual
Search
“Search for the Red ‘O’.”
Which is parallel search?
Pop-out (automatic, bottom‐up)
There was one red item on the screen; so it immediately draws attention
Which is serial search?
Conjunction
(need to search whole display, top-down)
There were several red and green ‘O’s and ‘X’s on the screen, so you had to intentionally search.
Object-‐based
ADen<on:
Behavior
Behavior and fMRI
Benefit for whole object!
Attention spreads across object;
Additional cost to move attention between objects
Object-‐based
Attention:
fMRI
Attend to faces or houses
• Increase in FFA activity when attending faces
• Increase in PPA activity when attending houses
• Same stimuli! A picture of a face and a picture of a house were superimposed on each other.
FFA (fusiform face area)
&
PPA (parahippocampal place area)
Attentional
control
networks
Attentional control network:
voluntary, top‐down
(priming signal to sensory areas,
e.g., increase baseline firing rate)
Attentional re-orienting network:
involuntary, bottom-up capture by unexpected events (“circuit-‐breaker” to re-‐orient to new relevant stimulus)
Top‐down control
vs
bottom‐up capture:
Neurophys
• Task:
maintain attention at “saccade goal” location
(top‐down)
• On some trials, distraction appears in different location
(bottom‐up)
• What happens to attentional focus?
Neural priority maps (parietal):
Top‐down attention»_space;» Distractor captures attention»_space;» Top‐down attention regained
Attentional Control Networks
• Dorsal fronto‐parietal network:
top-down, goal-directed attention
(stay focused on goal)
• Ventral fronto‐parietal network:
bottom-‐up, stimulus-driven attention
(remain alert to environment)
• Subcortical network:
arousal, eye movements, orienting/shifting
Balint’s
Syndrome
• Bilateral damage to posterior parietal & occipital cortex
• Symptoms
– Difficulty making eye movements/orienting attention
– Difficulty w/ visually guided reaching
– “Simultagnosia”: can only perceive 1 object at a time
Unilateral
spa<al
neglect
(Neglect)
• Brain damage to attention network in one hemisphere (typically right parietal/frontal).
• Symptoms
– Deficit in attending to & acting toward left side
– “Extinction” = when presented with stimuli in both left and right visual fields, only perceives/responds to right
– Not a sensory deficit; can perceive left‐side stimuli in isolation
– Also neglect in memory (visualizations)
Different types of neglect
(a) Extrapersonal space
vs
(b) Object-‐based
Cortical Damage in Neglect
Superior Parietal Lobule
Inferior Parietal Lobule
TPJ
Temporoparietal Junction (TPJ)
an area of the brain where the temporal and parietal lobes meet.
The TPJ incorporates information from the thalamus and limbic system, as well as from the visual, auditory, and somatosensory systems.
The TPJ also integrates information from both the external environment and from within the body. The TPJ is responsible for collecting all of this information and then processing it.
This area is also known to play a crucial role in self-other distinctions processes.
Damage to the TPJ has been implicated in having adverse effects on an individual’s ability to make moral decisions and has been known to produce out-of-body experiences (OBEs). Electromagnetic stimulation of the TPJ can also cause these effects. Apart from these roles that the TPJ plays, it is also known for its involvement in a variety of disorders such as amnesia, Alzheimer’s disease, and schizophrenia.
Neglect:
Recovery
?
Neglect:
Eye
Tracking
gaze Bias
