Week 7: Attention Flashcards
The human brain cannot process all this information simultaneously,
that is, there is __________________.
limited processing capacity
Since there is limited processing capacity in the brain, what type of system do we need?
a system that
helps to select relevant
information and to filter out
irrelevant information = the
attention system.
In the brain, What do the attentional bottleneck reflect?
The brain has a limited capacity to process information.
what does the brain’s limitation require?
the selective filtering of relevant stimuli while disregarding others.
what does the brain’s limitation of capacity arise from?
restricted perceptual and attentional resources, competition for cognitive processing, and the
need for strategic allocation based on goals and priorities.
at what stage of processing is the bottleneck of attention occurring?
at the response selection stage of information processing, meaning that the limitation in processing capacity happens when deciding which response to make to a stimulus, rather than during early sensory perception or motor execution.
what does selective auditory attention allow for in The cocktail party phenomenon?
Selective auditory attention allows focus on a single conversation in a noisy environment.
How does attention help us in the cocktail party phenomenon?
Attention filters out irrelevant stimuli, enabling focus on a specific source.
What can break through the attentional filter during the cocktail party phenomenon?
salient stimuli, like hearing your name
cocktail party phenomenon
is a psychological phenomenon that allows people to focus on a single conversation or stimulus in a noisy environment
a neuropsychological test that assesses the brain’s ability to process and separate simultaneous auditory stimuli presented to different ear
Dichotic Listening
How is dichotic listening used for selective attention in a lab?
- Participants hear different auditory stimuli simultaneously in each ear through headphones.
- They are instructed to focus on one ear’s input (the attended channel) while ignoring
the other (the unattended channel)
What does the method of dichotic listening investigate?
how attention
affects auditory processing and how much
unattended stimuli are processed.
What does focusing of one ear do?
enhances encoding of
stimuli in that ear while diminishing the processing of unattended inputs from the opposite ear.
a theory that suggests our brain filters out irrelevant sensory information at a very early stage of processing, based on basic physical features like pitch, color, or location, before the information is fully analyzed for meaning
Early Selection Model
In early selection models, Incoming sensory information is briefly stored in a ______________.
sensory register
In early selection model of filtering sensory input, what does attention function as?
a selective filter, allowing only attended stimuli to pass through for further
processing.
In early selection model of filtering sensory input, what happens to the filtered information?
filtered information then moves through a selective filter stage, while unattended information is
largely disregarded.
What does Broadbent’s model/ early selection model provide a foundation for?
understanding selective attention and early perceptual
processing.
What is the early selection model of top-down gating?
Top-down influences from higher-order executive processes regulate early perceptual processing.
in the early selection model of top-down gating, when does gating occur?
when processing capacity is limited, allowing selective Filtering of incoming
information based on relevance and importance.
explain the limits to selective attention: Intrusion of Unattended
Unattended but salient stimuli can intrude into conscious awareness
what is an example of Intrusion of Unattended?
Unexpectedly noticing your name or interesting information from another
conversation.
what do Early selection models allow for?
exceptions
where highly relevant information can break
through
What does the limit of Intrusion of Unattended suggest about attention filtering?
Suggests attentional filtering is flexible, allowing certain stimuli to reach higher processing stages
what do early selection models suggest about unattended info?
unattended information is lost
observations of unattended information intruding into awareness show what?
some stimuli can reach higher stages of analysis.
what do late selection models propose?
that attention acts after
sensory inputs are fully
processed, often at stages where
information has been encoded
semantically.
Feature Integration Theory
Unattended information is not fully filtered from
analysis. When perceiving a stimulus, features like color,
form, and motion are processed automatically and in parallel.
what does Feature Integration Theory say about focused attention?
Focused attention is required to bind these
features into a coherent perception
in the feature integration theory, what happens without attention?
features remain unbound and
can lead to perception errors
explain Helmholtz’s Experiment: Early Evidence of Selective Attention
- Helmholtz’s attention experiment required
subjects to fixate their gaze on a single point
while viewing a complex visual scene. - While maintaining fixation, attention was
directed to specific areas using a light cue, and
subjects were asked to report what they saw
what does Helmholtz’s experiment demonstrate?
that perception could be enhanced by focusing attention on a particular location in the visual field, though this came at the cost of processing other areas
involve attending to a
location without moving the eyes or gaze to
that location
Covert shifts of attention
involve attending to a
location and moving the eyes or gaze to that
location
Overt shifts of attention
occur when attention is drawn
by a highly salient stimulus, driven by bottom-up mechanisms.
Exogenous (reflexive) shifts of attention
involve the voluntary, top-down
allocation of attention, such as intentionally searching for a face in a
crowd.
Endogenous shifts of attention
Posner Cueing Paradigm
a target can appear in one of two locations, and the observer reports whether the target is present (yes/no). We are quicker to detect objects at places that have been cued before, that is, where previously a salient stimulus was presented
Endogenous Cueing in Posner Cueing Paradigm
voluntary, top-down
Exogenous Cueing in Posner Cueing Paradigm
reflexive, button-up
Operates on a specific
spatial segment of the visual
scene
using spatial attention as a spotlight
What did the Posner cueing paradigm reveal about reaction times?
reaction times for expected locations are significantly shorter than those for unexpected (invalid) and neutral locations.
Can shift voluntarily
through top-down
(endogenous) mechanisms
or be automatically drawn
by salient stimuli through
bottom-up (exogenous)
processes
Spatial Attention
Enhances visual processing
of the attended area.
spatial attention as a spotlight
Limits of Voluntary Spatial Attention
relatively slow deployment time, a restricted field of focus, susceptibility to distraction, limitations in peripheral vision, and the inability to effectively attend to multiple locations simultaneously
What are ERP studies for attention?
Attention increases responses across multiple ERP components.
in ERP studies, what does the P1 response reflect
early enhancement of sensory processing driven by attention.
what does Selective Enhancement of Visual Responses say about attention?
increases responses to visual stimulation in the visual cortex
It selectively enhances responses to preferred stimuli within the receptive field (RF).
What does attention boost?
boosts responses across visual cortex
explain O’Connor’s study using checkered boards
attention modulated neural activity in the human lateral geniculate nucleus (LGN) in several ways: it enhanced neural responses to attended stimuli, attenuated responses to ignored stimuli and increased baseline activity in the absence of visual stimulation. The LGN, traditionally viewed as the gateway to visual cortex, may also serve as a ‘gatekeeper’ in controlling attentional response gain
Effect of attention is stronger for _____________ visual areas
anterior (higher-order)
Attention boosts response in the ____________
LGN
Attention increases activity to _____________ of V1 simple cell
ON and OFF subregions; i.e., subregions that were either excited or inhibited by visual stimulation
Visual stimulation activates __________ regions of visual maps corresponding to the lower visual field.
dorsal
Focusing attention on the lower visual field enhances activity in _________ extrastriate areas
dorsal
Attention to the upper visual field enhances activity in more __________ visual regions
anterior
How was scale-dependent attentional enhancement studied?
Subjects attended to arrays and reported spatial shifts.
what did small shifts in space activate?
the posterior visual cortex
what did large shifts in space activate?
activated anterior regions
what does attention to a stimulus amplify?
its evoked neural responses compared to
when the same stimulus is unattended
Neural activity evoked by unattended stimuli what?
suppressed relative to
attended stimuli.
when do both enhancement and suppression occur?
across all stages of visual
processing, including early structures such as the thalamus (e.g., LGN) and
higher-order visual cortical areas.
The dynamic modulation allows the brain to do what?
to prioritize relevant information while Filtering out distractions, improving perceptual efficiency and focus
when multiple stimuli presented simultaneously in the visual field, how are they processed?
together (not independently)
when multiple stimuli presented simultaneously in the visual field, what are they competeing for?
neural representation
When the multiple stimuli are competing for neural representation. what does the competition result in?
a mutual reduction, or
suppression, of neural activity
for the competing stimuli
What happens to the
competition if attention is
directed to one of the stimuli?
the sensory interaction with the reference stimulus becomes simultaneous
- Attention to a stimulus counteracts
suppression from nearby competing
stimuli. - Neural responses to the attended stimulus
can be as strong as if it were presented
alone. - By resolving competition, attention filters
out irrelevant information from nearby
distractors
Biased Competition Theory of Attention.
what is the evidence for biased competition with fMRI?
the amount of signal change in the competition being tracked with fMRI
why do the predicted SEQ > SIM
effects seen in extrastriate cortex but
less so in early visual happen?
the size of receptive fields in V1 are smaller, only analyzing part of the image, not all the pictures.
biased competition: Sensory Interactions hypothesis
The fMRI signal for visual stimuli presented simultaneously in
nearby locations should be weaker than for stimuli presented
separately, due to suppressive sensory interactions.
biased competition: attentional modulation hypothesis
Directed attention should counteract the suppression caused by
nearby stimuli.
explain the Sensory Competition Within the Receptive Field
Sensory interactions among multiple stimuli were suppressive, indicating competition for neural representation in the human ventral extrastriate cortex.
* These suppressive interactions scaled with the receptive field sizes of neurons in V1, V2, V4, and TEO/IT.
What does attention being added do to the competition?
The difference between
sequential (SEQ) and
simultaneous (SIM)
stimulus presentation is
reduced when attention
is directed.
Where is the effect of attention reducing suppression the strongest?
extrastriate visual areas
Explain Biased Competion: Attentional Filtering
- Directing attention to one stimulus location counteracts suppression from nearby stimuli, enhancing processing at the attended location.
- Suppression modulation in the ventral extrastriate cortex may be a key mechanism by which attention Filters out irrelevant information in cluttered visual environments.
in the V4, what is shown when all stimuli is presented simultaneously?
the sequential is higher than the simultaneous
describe Filtering Distractions Through Top-Down and Bottom-Up Attention
- Modulation of suppression in the ventral
extrastriate cortex may be a key mechanism by which attention filters out unwanted information in cluttered visual scenes. - The same mechanisms apply when bottom-up (stimulus-driven) factors draw attention to filter out distractor information
what is not gonna help you find waldo in the picture?
spatial attention
explain Feature-Based Attention
a mechanism that allows the brain to focus on a specific feature of an image, such as color or orientation
what should we do instead of feature search when searching through an array with similar features as our desired stimuli, what should we use?
do a conjunction search
a visual search that involves finding a target by considering multiple features, such as color and shape
conjunction search
Subjects cued to attend to color
(C) or motion (M)
feature based attention
Attending to color increases
activity in ________
V4
Attending to motion increases
activity in _______
MT
when subjects are cued to pay attention to a direction of an arrow, what is the spatial condition?
an arrow cued the location to attend.
when subjects are cued to pay attention to a direction of an arrow, what is the feature condition?
an arrow indicated the direction of
motion.
do both spatial and feature types of attention improve performance?
YES
How was spatial attention different from feature attention?
Spatial attention had stronger effects and
appeared more rapidly
what do ERPs reveal about the Neural Signatures of Spatial and Feature-Based Attention?
ERP patterns reveal distinct processing
for spatial and feature-based attention
what do spatial and feature types both do?
selectively process visual
stimuli through separate mechanisms
using ERP: Spatial attention is reflected in the _________________
early P1 component
using ERP: feature-based attention appears in _________________
longer-latency waveforms
explain the task of measuring Neural Signatures of Object-Based Attention
On each trial, either the face or the
house moved while the other remained
still.
* Task: Attend to either the moving or
the static object.
Attending to faces enhanced responses
in the _______
FFA
Attending to houses enhanced
responses in the _________
PPA
Which areas are involved in the top-down control of the attentional response modulation in ventral extrastriate cortex ?
PG and PFC
describe the Probing the Attention Network with fMRI
they wait a bit before presenting stimulus, there is a large increase of response in the FEF when performing the act of giving attention
How does the V4 respond compared to the FEF?
With the V4, increase in response occurs once the stimulus is presented.
Where is there similar activation during directed attention w/o stimulation?
frontal and parietal lobe
explain the Frontal-Parietal Network for directed attention
- During directed attention to a target location in the presence and in the absence of visual stimulation, a distributed network of areas in frontal and parietal cortex was activated.
- This network may serve as the top-down feedback source for the attentional effects found in visual cortex
the dorsal attention network top-down or bottom up?
top-down
how do we know frontal and parietal regions
are important for attentional control?
LESIONS
the ventral attention network top-down or bottom up?
bottom-up
- Bilateral and topographic organization.
- Goal-directed, top-down control of attention.
- Focuses on relevant locations and potential
targets. - Damage reduces modulation of visual activity by
attention.
Dorsal Attention Network
- Right-lateralized system.
- Stimulus-driven, bottom-up attention.
- Detects salient stimuli and reorients attention to unexpected events.
- Damage to the right inferior parietal cortex can cause neglect, impairing awareness of stimuli on the opposite side
Ventral Attention Network
Impaired ability to direct attention to the
contralateral hemifield in patients with
unilateral brain damage.
Not a visual deficit—patients can detect
salient stimuli when presented in
isolation
Visuospatial Neglect
when two stimuli appear in both hemifields, what happens?
the contralesional stimulus is
not perceived (extinction)
what does extinction suggest?
that sensory inputs
compete for attentional resources
a neurological disorder characterized by an inability to perceive, report, or orient to stimuli on one side of space, typically the contralateral (opposite) side of a brain lesion
visuospatial neglect
the syndrome of visuospatial neglect is a common consequence of ___________________
unilateral brain injury
how do you test visuospatial neglect?
cancellation test, drawing test, reference point test
Lines circles, letters, or stars are drawn in random positions on a sheet of paper and presented to patients who are asked to cancel or cross out all the targets. Spatial neglect patients may fail to cancel targets on the contralesional side.
cancellation test
a patient is asked to draw a clock face, including all the numbers and the hands set to a specific time, allowing clinicians to observe any asymmetry or omissions in the left side of the clock, indicating potential neglect on that side.
drawing test
when having to navigate somewhere, they will ignore the side they cannot see
reference point test
visual stimuli still activate visual
regions in occipital lobes even if they are unaware of items.
* Auditory and tactile judgments are also affected (e.g.
sounds on left are mislocalized, but still heard)
visuospatial neglect
What can visuospatial neglect patients do when cued to ATTENTION?
Patients can orient to a cue on the neglected side if they
are cued to attend but they have problems shifting
attention from the un-neglected side to the neglected side
results from bilateral
parietal-occipital damage, leading to
severe deficits in spatial attention and
coordination
Balint’s syndrome
What is Balint’s syndrome characterized by?
simultanagnosia
(inability to perceive multiple objects),
optic ataxia (impaired visually guided
reaching), and ocular apraxia (difficulty
making voluntary eye movements)
inability to perceive multiple objects
simultanagnosia
impaired visually guided
reaching
optic ataxia
difficulty making voluntary eye movements
ocular apraxia
what do the impairments of Balint’s syndrome make it difficult to do?
for individuals to interact with their
environment, affecting daily activities
and perception.
is a defining symptom of Balint’s
syndrome, causing an inability to perceive multiple objects at once.
simultanagnosia
in simultanagnosia, what do patients fail to do?
Patients can see individual objects but fail to integrate them into a full scene
Where does simultanagnosia occur alongside?
optic ataxia (impaired visually guided reaching) and ocular apraxia (difficulty making voluntary eye movements)
what type of lesions are Simultanagnosia linked to?
bilateral dorsal and occipital lesions,
disrupting spatial attention and visual scene integration.
describe the cookie theft test?
test for simultanagnosia;
* A person with simultanagnosia can describe the dishes being cleaned but won’t notice the overflowing sink.
* They can describe cookies being taken
from the jar but won’t see the child
about to fall.
What are eye movements in Simultanagnosia like?
- Eye movements are spatially disorganized and erratic.
- When asked to “read”
a clock, individuals focus on uninformative details rather than the
overall structure.
what is the neural Architecture of attention
PPC & FEF -> TEO -> V4 -> V2 -> V1 -> LGN
Visual Neglect From Pulvinar Lesions effect
a patient may fail to perceive or respond to visual stimuli on the side of space contralateral to the lesion, essentially ignoring one side of their visual field due to an impairment in spatial attention processing, which is a key function of the pulvinar.
plays a crucial role in attention by contributing to the allocation of attentional resources, particularly in directing visual attention and regulating arousal levels, through structures like the superior colliculus (SC) which is involved in eye movements and spatial attention, while interacting with cortical regions to facilitate the selection of relevant information from the environment; essentially acting as a key component in the “bottom-up” attention process.
subcortex region
what is the pulvinar role in reorienting attention?
- Inactivating the pulvinar with
muscimol had no effect on
ipsilesional performance - Slower response times for target
detection in contralesional
space following pulvinar
inactivation - Enhancing pulvinar activity with
bicuculline improved response
times when reorienting to the
contralesional side
what is the superior colliculus role in covert attention?
- Microstimulation of the superior
colliculus enhanced performance in a spatially specific manner. - Results converge with prior work
showing that deactivating the superior colliculus reduced performance when a target appeared with distractors (Desimone et al., 1990). - The superior colliculus contributes to covert attention, allowing focus without moving the eyes
Attention toward a stimulus increases activity in the ________ compared to when attention is directed away.
LGN
Attention toward a stimulus decreases activity in the _________________.
thalamic reticular nucleus (TRN)
Since the TRN inhibits the LGN, this reduction in TRN activity results in what?
in less inhibition, allowing the LGN to
enhance visual processing
The ___________ is activated during directed attention.
dorsal pulvinar
Lesions in the dorsal pulvinar region lead to ___________
thalamic neglect
The ______________ plays a key role in covert attention, enabling focus without eye movements
superior colliculus
The ____________________ regulates LGN activity, modulating visual processing during attention.
thalamic reticular nucleus (TRN)
