Attention and Consciousness Flashcards
This patient has Balint’s syndrome, a severe disturbance of visual attention and awareness that results in only one or a small subset of available objects being perceived at any O…… time,
and these being M……….. in space.
One
Mislocalized
The patient can “see” each of the objects presented by the doctor- the comb, the spoon, and even the numbers on the clock.
But he fails to see them all T…………………. and cannot accurately describe their L…………….. with respect to each other or to himself.
Together
Locations
The fact that we are C………………………… aware of
only a S…………………………… of the vast amount of information available to our sensory systems from moment to moment.
Consciously
Small bit
In this chapter we investigate the mechanisms of attention and awareness. First, we will learn that attention involves both
T……-D………… (V…………………),
goal-directed processes and
B…………….-U…. (R…………………..)
stimulus-driven mechanism, and that they are in dynamic competition for control of the momentary focus of attention.
Top-down (voluntary)
Bottom-up (reflexive)
These effects of attention influence the way information is P………………… in the brain,
and can occur E………. during sensory processing. Widespread brain networks interact to enable us to
attend to relevant events and, importantly, to ignore those that are irrelevant.
Processed
Early
We can C………………..
the focus of our attention.
Control
In this chapter we focus on the mechanisms of selective attention- those cognitive processes that enable organisms to
P……………………. R……………………. I……………… thoughts,
or actions while ignoring irrelevant or distracting ones.
Process Relevant Inputs
We can divide attention into two broad categories:
(a) voluntary and
(b) reflexive.
Voluntary attention, a top-down,
G………………- directed influence,
is our ability to
I………………….. attend to something.
Reflexive attention, a bottom-up, stimulus-driven influence, describes the phenomena in which a sensory event captures our attention.
Goal
Intentionally
In 1894, Hermann von Helmholtz constructed a screen on which L………………..
were painted at various distances from the center.
Letters
Helmholtz noted that the screen was too large to view without moving the eyes.
Nonetheless, even when he kept his eyes fixed right at the center of the screen, he could
D………………………… I……….. A………………………
where he would pay attention; that is, he made use of something we now refer to as
C………………….. A………………………….
Decide In Advance
Cover Attention
By covert we mean that the location to which he directed his attention could be
D…………………………..
from the location at which he was locking.
Different
Through these covert shifts of attention, Helmholtz observed that, during the
B………………………period of illumination,
he could P………………………………….
letters located within the focus of his attention
B…………………………. than letters that fell
O……………………. T…………………. F…………………………
of his attention, even when his eyes remained at the
C………………………….
of the screen.
Brief
Perceive
Better
Outside The Focus
Center
“These experiments demonstrated, so it seems to me, that by a
V…………………………. K…………………….
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.”
Voluntary Kind
British psychologist E. C. Cherry (1953) examined the so-called
C……………………. P………………….. E…………………….
Cocktail Party Effect.
By S…………………………………… attending, y
ou can perceive the signal of interest amid the louder noise, and remain charming in a difficult social context.
Selectively
These changes in
Global…………….. S………………….. O……….A……………………… can be related to specific neurons in the brain and are reflected by changes in the electroencephalogram (EEG),
the S……………. V……………………….
fluctuations that accompany neuronal activity in the brains of all animals.
Global State Or Arousal
Small Voltage
The EEG is a clear indicator of the state of global arousal and sleep in normal subjects; one can
P…………………………….
of change from wakefulness to sleep and to different stages of sleep by viewing the EEG alone.
Pinpoint
Attentive behaviors have a
H………………………………… structure.
At the most global level are states of alertness such as sleep and wakefulness
W…………………………..
includes more and less attentive and more and less selective states:
D………………… A………………….. and
H………………………..
such as when a life-threatening situation arises.
Hierarchical
Wakefulness
Drowsiness Alertness
Hyperalertness
At a finer level of description are levels within each
Awake
global state of awareness; here we reach levels of description that are appropriate for considering
S…………………………….,
as with the cocktail party effect described in this chapter.
Awake
Selectivity
For instance, finding that neurons are more active when an animal is
E………………………..
performing a task, as compared with drowsily watching stimuli, might be an example only of a nonspecific state difference induced by the arousal of the task, and
N…………… E……………………………..
of neuronal mechanisms of selective processing.
Excitedly
Not Evidence
Cherry investigated the effect by providing
C…………………………..
speech inputs to the two ears of a normal subject through headphones
(D…………………… L………………………..).
In different conditions he asked people to attend to and verbally
“S………………………………”
(immediately repeat each word) speech coming into one ear, while simultaneously ignoring similar inputs to the other ear.
Competing
(Dichotic Listening)
“Shadow”
Cherry discovered that, when different speech inputs were played into each ear and the subjects were asked to shadow what was played into only one ear at a time, they could
N…………………… R……………………………
any details of the speech in the
U……………………. E…………..
Not Report
Unattended ear
Are the effects of selective attention
E…………………..
- that is, before extensive perceptual analysis?
Or do they occur
L……………
- after the information has been analyzed, but before a later stage of processing, such as that associated with
Encoding
the information as a semantic code or prior to the control of actions.
Early
Late
Encoding
The British psychologist Donald Broadbent (1958), working at Cambridge University. He conceptualized the
I……………………..-P…………………. S………………………,
a term that encompasses all aspects of the brain’s processing of data, including sensory inputs, as having a
L………………………-C………………………
stage through which only a certain amount of information can pass.
Information-processing System
Limited-Capacity
Broadbent described this mechanism as a
G……………………….
that could be opened for attended information and
C……………………………….
for ignored information. Thus, Broadbent argued for information selection
E…………………………
in the information-processing
S…………………………..
Gate
Closed
Early
Stream
Early selection, then, is the idea that a stimulus need to be
C………………………… P………………………….
analyzed before it can be selected for further processing or rejected as irrelevant.
Completely Perceptually
Subjects were often able to report when their own name was presented on the unattended channel.
This concept of
I…………………………………
of the unattended inputs led many to believe that all information was
E……………………….. analyzed,
regardless of whether it was attended or ignored later during processing.
Intrusion
Extensively
Models of late selection hypothesize that attended and ignored inputs are processed
E…………………………
by the perceptual system, reaching a stage of
S…………………………. (meaning)
encoding and analysis.
Equivalently
Semantic
Instead, selection takes place at
H………………. S……………………
of information processing that involve
I……………………… D……………………………..
about whether the stimuli should gain complete access to awareness, be encoded in memory, or initiate a response.
Higher Stages
Internal Decisions
Anne Treisman (1969) proposed that perhaps unattended channel information was not
C………………………… G……………………
from higher analysis but was merely
D…………………………..
or attenuated- a point with which Broadbent agreed.
Completely Gated
Degraded
Early-selection versus late-selection models were therefore modified to make
R…………………..
for the possibility that information on the unattended channel could reach
H……………………… S……………………..
of analysis, but with greatly
R…………………………… S…………………………
strength.
Room
Higher Stages
Reduced Signal
Limited-capacity is a concept that naturally flows from the observation that human performance
S………………………
when overloaded by multiple inputs.
Suffers
The system must make
H………….
“decisions” about what is selected for extended processing or gains access to awareness because the
C…………………………..
limitations result processing
B………………………………..
Hard
Capacity
Bottlenecks
Presumably the information-processing system evolved
S………………………. M…………………………..
to control information flow these bottlenecks and to establish priorities.
Selection Mechanisms
In these cuing tasks, the focus of attention is
M……………………………….
by the information in the cue. Cues can
D………………….
voluntary attention or be used to
A………………….
reflexive attention.
Manipulated
Direct
Attract
In studies of voluntary spatial attention using cuing tasks, participants are asked to
R………………… as F……………….
as they can following the
P…………………………….
of a target stimulus.
Respond
Fast
Presentation
They are instructed that the most likely location for the next target is the one indicated by a
P………… C…………………
such as an arrow pointing to that location; this is known as endogenous cuing because the
O………………..
of attention to cue is driven by the subject’s
G………………….. (perform the task as
I…………………)
rather than merely its physical features .
Prior Cue
Orienting
Goals
Instructed
When a cue correctly predicts the location of the subsequent target, we say we have a
V…………… T……………….
If the relation between cue and target is strong-that is, the cue usually
P…………………….
the target location (80% of the time)-then subjects
L………………..
to use the cue to
P……………………
the next target’s location.
Valid Trial.
Predicts
Learn
Predict
Sometimes, though, the target is presented at locations
N……….
indicated by the cue, in which case we have an Invalid trial.
Finally, the cue might give
N….
information about the most likely location of the
I……………………………
target; this situation is referred to as a
N……………………. trial.
Not
No
Impending
Neutral
That is, if the target appears where subjects expect it, they are
F…………………..
to respond to it; they are also slower to respond to targets at unexpected locations.
Faster
The spatial cuing
P…………………………..
popularized by Michael Posner and colleagues at the University of Oregon.
Paradigm
The function of
L…………….
expectancy are called
B………………….
(speeding of reaction time) and
C…………………
(slowing of reaction time) with respect to the neutral situation in which the subject does not expect the target at one location more than another.
Location
Benefits
Costs
These effects have been attributed to the influence of
C……………
attention on the efficiency of information processing.
Covert
The
S…………………….
is a metaphor to describe how the brain may attend to a spatial location.
Spotlight
The attentional spotlight may affect reaction times by influencing sensory and perceptual processing;
hence, representations of attended-location stimuli are
E……………………………..
with respect to unattended-location stimuli.
Enhanced
The lecturer leaves the door to the hallway open and, in the middle of lecture, someone
W…………… D……………….
the hallway passing the open door?
Walks Down
It is an example of
R………………………. (A………………………………)
attention leading to over orienting to the sensory stimulus-
O………………….
because heads and eyes turn toward the event in the hallway. But even in the absence of overt signs of orienting, covert attention can be
A……………………………
to sensory events.
Reflexive (Automatic)
Overt
Attracted
One way to demonstrate the effects of reflexive attention is to examine how a task-irrelevant
F…………..
of light somewhere in the
V…………….. F…………….
affects the speed of responses to subsequent task- relevant target-stimuli.
Flash
Visual Field
This method is referred to as
R…………………….. C……………………..
or exogenous cuing because attention is controlled by the
L……………….-L…………………….
features of external stimuli and not by internal voluntary control.
Reflexive Cuing
Low-Level
When more time passes
B……………………
the task-irrelevant cuing light flash and the target (more than about 300 ms), the pattern of reaction time effects is
R…………………:
Subjects now respond more slowly to these stimuli. This slowing of responses is called the inhibitory aftereffect or, more commonly,
I…………………. of R………………………
Between
Reversed
Inhibition of Return
The automatic orienting system has built-in mechanisms to prevent reflexively directed attention from becoming
S…………..
at a location for
T………….. L……………………
(more than a couple hundred milliseconds).
Stuck
Too Long
Does this mean that things that attract our attention reflexively
(C……………. be A…………………….)
for longer than a couple of hundred milliseconds? No. If the event is important, we can rapidly
I…………………………
our voluntary mechanisms to sustain attention longer, thereby
O…………………………….
the inhibition of return.
Can’t be Attended
Invoke
Overriding
The mechanisms of visual search were investigated and modeled by Anne Treisman. A basic observation from their work is that the time it takes
T…… F……….
a target among distracters is shorter (i.e., target are located quickly) and
I……………………….
of the number of distracters in the array if the target can be identified by a
S……………………….
feature such as color (e.g., a red O among green Xs and Os).
To Find
Independent
Single
This is known as conjunction search because the target is defined by the
C…………………………… of T………………..
or more stimulus features
(e.g., the color red and the letter O).
Conjunction
Two
Jeremy Wolfe showed that, when
D…………………….
movements of attention were required in a visual search task, people responded
M…………… S……………………
than when deliberate movements of attention were not required and search was permitted to proceed automatically.
Deliberate
More Slowly
That is, the brain automatically scans the visual world with a fast,
A…………………. S…………………….
of attention.
Automatic Spotlight
As demonstrated earlier, selectively attending to spatial locations, either voluntarily or reflexively,
L………………
to changes in our
A…………………..
to detect and respond to stimuli in the sensory word.
Leads
Ability
We will add that spatial attention also influences
A………………….. and
S…………………….. information
P…………………………
Auditory
Somatosensory
Processing
We can also ask whether selectively attending to a stimulus feature (e.g., motion, color, shape) or objects properties (e.g., face versus a house) similarly
I…………………………..
information processing.
Influences
Marissa Carrasco’s experiments demonstrated that
P……………………….
attention to a visual
F…………………………..
of a stimulus (in this case motion direction) led to
I……………………………
performance.
Precuing
Feature
Improved
Interestingly, the effects of attention arose earlier (at shorter lags between the cue and the target) for the
S…………………….. attention condition
than for the feature attention condition.
Spatial
These shorts of findings for feature attention clearly demonstrate that attention can be directed in advance to
N…………………………..
features of target stimuli, as well as to
S………………………………. locations.
Nonspatial
Spatial
Raúl Hernández-Peón investigated that some neurons in the central nervous system
P………………….
into the synapse on sensory input neurons in the peripheral nervous system.
Project
For example, each neural relay in the ascending auditory pathway send
R………………….
axons
B……………….. D……………………
to the preceding processing stage, even out to the cochlea in the form of the olivocochlear bundle (OCB).
Return
Back Down
By applying electrical stimulation to the cortex, it can be show that activity in the cortex can activate the
D………………………………………..
OCB pathway all the way to the cochlea.
Descending
The D…………………………
projections of the OCB might exert
T………..-D………………… C………………………
over subcortical auditory regions that project to the cortex in the service of
E…………………….
attentional gating of auditory inputs.
Descending
Top-Down Control
Early
These researches reported that the amplitude of
A…………………..
was G…………………….
in the cochlear nucleus when the animals
A………………………..
to the sounds compared to when they ignored the sounds while visually attending to the mice.
Activity
Greater
Attended
They interpreted these neurophysiological findings as evidence that
A…………………………
could affect the
E……………………………
stages of sensory processing- strong evidence for early-selection theories.
Attention
Earliest
By designing clever, well-controlled experiments, researchers were able to demonstrate that the
E…………….-R………………. P……………………. (ERP)
elicited by stimuli
V…………………………
as a function of the subject’s attentional
S…………………………………
Event-Related Potential
Varied
State
The ERP response to a physically identical stimulus was different when that stimulus was
A……………………….. C………………………….
to when it was ignored.
Attended Compared
Steven Hillyard and his colleagues discovered that auditory sensory ERPs were
E……………………..
in amplitude when stimuli were
A…………………………..
compared with when they were ignored.
Enlarged
Attended
This effect in the ERPs appeared as a deflection in the ERP waveform known as the
A……………………. N..
potential, so named because it is the first of the large, negative-polarity deflections in the signal-averaged waveform.
Auditory N1
The N1 component is a
S…………………..-E………………………….
wave with a peak latency of less than
………………… ms
after stimulus onset. Given that this sensory response was
L…………………….
to manipulation by covert attention, these data provided evidence in support of
E………………….-S…………………….
models of attention.
Sensory-Evoked
90
Labile
Early-Selection
Larger N1 responses to tones presented to the
A……………………
ear. In addition, they observed that even earlier waveforms- those occurring between 20 and 50 ms after stimulus onset- were also
D………………………..
as a function of
S………………………….. auditory attention.
Attended
Different
Selective
This finding, the
P………-………….. E……………….,
named for its positive polarity and latency of occurrence (20-50 ms) after stimulus onset, provided extremely
C…………………..
evidence in support of early-selection models, because
the T………………………….
of the P20-50 ERP suggests an
E………………………….. S……………………
of processing,
P20-50 effect
Compelling
Timing
Early Stage
The primary auditory cortex or even earlier, such as from the
M…………….
geniculate nucleus of the
T……………………………,
the auditory thalamic relay.
Medial
Thalamus
These investigators identified a
M…………………………………….
correlate of the early electrical P20-50 attention effect:
the so-called M20-50 attention effect (M for magnetic).
Magnetic
The researches localized the M20-50 effect to the auditory cortex in
H………………….. G……………………..
Heschl’s Gyri
Similar magnetic effects can be observed in the time range of the N1 attention effect (the so-called M1 attention effect), and these effects also appear to be generated within the
A……………………..
cortex, but at a
L……………………….
stage of neural processing than the shorter-latency M20-50.
Auditory
Later
Attention therefore, can affect auditory stimulus processing at
I………………………
cortical stages of processing.
Initial
Longer latency changes in an ERP or ERF waveform reflect attentional
S……………………
involving the stimuli’s
H…………………………
order properties, such as a speaker’s voice or
S……………………………….
meaning.
Selection
Higher
Semantic
Electrical recordings of human auditory processing from scalp electrodes can
P…………. U……
sensory activity as early as the
B……………………………….
relays, and even the compound action potential of the auditory
N………………….
itself.
Pick Up
Brainstem
Nerve
This activity is called the
auditory B……………………….. response (ABR)
and is manifest as voltage deflections in the auditory ERPs with latencies between
…………… and …………… ms
after stimulus onset.
Brainstem
1 and 10
Can these subcortical ERPs be modulated by selective attention? The answer, from many studies, is that voluntary selective attention in the auditory system does
N……. A……………………
to involve modulations of
S…………………………. auditory neurons
as measured by the ABR recordings,
E…………………….
when attention must be very highly focused.
Not Appear
Subcortical
Even
Marie-Helene Giard indicated that the otoacoustic emissions emanating from the
E….. C……………….
are modulated by auditory selective attention.
Ear Canal
Otoacoustic emissions are minute sounds actually produced by
M……………………
changes in the cochlea during hearing. These can be recorded with a sensitive
M…………………………….. placed in the
ear C………………………….
Mechanical
Microphone
Canal
Changes in these sounds with attention could reflect attention-related
M……………………………….
of the mechanical properties of the cochlea, which
M………………..
represent a form of attentional control.
Modulations
Might
Over the contralateral posterior scalp, beginning about 70 ms after the onset of the stimulus, an increased
P……………………. V…………………………
response can be observed for the left stimulus when it is
A……………………………..
versus when it is ignored.
Positive Voltage
Attended
The response to the stimulus produces a sort of
“M………………..P…………..”
of voltage over the contralateral scalp, and the peak is
H……………………
if you will, for
A…………………………
as opposed to ignored stimuli.
“Mountain Peak”
Higher
Attended
Eason and Hillyard demonstrated that
M………………………..
in the visual ERPs begin as early as
………….-…………. ms
after stimulus onset.
Modulations
70-90
This attention effect is seen in an ERP component known as the
O…………………. P..,
the first major positive wave. When a visual stimulus appears at a location to which a subject is attending, the P1 is
L…………………………
in amplitude than when the same stimulus appears at the same location but attention is focused
E……………………………..
Occipital P1
Larger
Elsewhere
Interestingly, these early effects of
V……………………. selective attention
are not reliably found when attentional selection is based on
O……………………. stimulus features,
such as C…………….
(e.g., attend to the red circles and ignore the green ones),
S…………………….. F…………………….,
orientation, or conjunctions of these features.
Visuospatial
Other
Color
Spatial Frequency
Selection of visual inputs based on
H…………….. O…………………. P………………………
such as what object it is (e.g., attend chairs but ignore tables) does
N………………… L…………………….
to short-latency modulations of ERP amplitude. Attentional affects for these more complex tasks are observed
L…………………..
in the ERPs (greater than ………… ms latency).
Higher Order Properties
Not Lead
Later
120
The P1 attention effect has an onset
L……………………
of about
…………… ms
from stimulus onset, but what does this value reflect in terms of the
F……………………. A……………………….
of the visual pathways?
Latency
70
Functional Anatomy
Intracranial recordings of activity in primary visual cortex in humans indicated that the first volleys of afferent inputs into striate cortex (V1) take place with a latency
L……………………… than …………..ms,
and therefore the P1 attention effect reflects
C……………………… activity.
Longer
35
Cortical
The P1 attention effect have indicated that the
E……………..
spatial attention effects are generated in
E…………………………
cortex.
Earliest
Extrastriate
When our attention is
R……………………….
attracted to a location in the visual field by a
S…………………………………
event, is neural processing in the visual cortex
H………………………….?
The answer is
Y…………..
Reflexively
Sensory
Heightened
Yes
Under such conditions, response times are faster at the
C……………
location than at the uncued location, but only when the time between the cuing and target stimuli is short
(L…………. than about 250 ms);
with longer periods, this
E…………… R…………………….
producing inhibition of return.
Cued
Less
Effect Reverses
Joseph Hopfinger showed that when ERPs are recorded in response to target stimuli in this type of design, the early occipital P1 wave is
E…………………………
for targets that
Q…………………………..
follow a sensory cue at the same location versus when the sensory cue and target occur at different
L……………………………
Enlarged
Quickly
Locations
But as the time after cuing grows
L……………………..
this effect
R………………………
and the P1 response
D…………………………
and may even be inhibited, just as in reaction time measures.
Longer
Reverses
Diminishes
These data indicate that both reflexive (bottom-up) and voluntary (top-down)
S…………………….
in spatial attention induce similar physiological modulations in early visual processing.
Shifts
During both voluntary and reflexive attention, a focal
“S…………………….”
of enhanced perceptual processing is
F…………………….
on a discrete spatial location.
“Spotlight”
Focused
The probe elicited larger early visual responses (P1) at the
L…………………… of a
C……………………………
target than in regions where nothing other than distracters was present.
Location
Conjunction
This demonstration suggest that similar neural mechanisms for the early selection of visual information are engaged during
V…………….. S…………………….
for targets defined by the
C…………………….. of F………………………….
among distracters as are engaged during voluntary attention in cuing and sustained attention paradigms.
Visual Search
Conjunction
Features
Nonetheless, in both cases changes in early visual cortical information processing based on the
L…………………. of attention
can be observed, and these have apparently highly similar neural mechanisms.
Location
F………………………
attention acts as a
S…………………….
that enables spatial attention to be
D……………………..
to the location of a stimulus containing a relevant feature, whereupon more
D…………………………….
analysis within the focus of spatial attention can take place.
Feature
Signal
Directed
Detailed
Neurophysiological evidence
S………………………….
this later model, which has been predicted in numerous prior models.
Supports
In general, spatial attention produced the
S………………….-L……………………….
ERP signs of attention, but at slightly longer latencies a host of ERPs index nonspatial, feature-based attention (e.g., attending one color while ignoring another), and we will collectively refer to these as
F………………….. S………………………..
ERPs.
Shortest-Latency
Feature Selection
A human brain response with the pithy name N2pc, which has been identified by Steve Luck and Steve Hillyard (1994), indexes how attention
Z……………………
down to focus on objects in visual space when one is
S…………………………..
for a target.
Zooms
Searching
Experimental work has established that the N2pc component is a sign of the
C………………..
focusing of visual attention, and that it represents a stage of processing that occurs
B…………………..
the completion of object recognition.
Covert
Before
They found that 140 ms after search array onset, a feature selection ERP was generated in
V………………….. O…………………………………..
cortex.
Ventral Occipitotemporal
This feature attention effect was then quickly followed (about 30 ms later) by an N2pc response generated in
M…………….. A……………………
regions of the occipitotemporal cortex that indicated that the subjects were focusing spatial attention on the target.
More Anterior
These findings clearly demonstrate that feature selective attention
P………………….
visuospatial attention when the location of the target is not
K………………..
in A……………………..
as is always the case in visual search paradigms.
Precedes
Known
Advance
Electrophysiological and neuromagnetic recordings provide
E…………………………
strong evidence in support of the concept of
E………………………..
selection.
Exceptionally
Early
The general model supported by these data is that
I……………………..
sensory signals can be
A…………………………
within the sensory-specific cortex when stimuli containing the relevant
P…………………………….
features (those to be attended) are encountered.
Incoming
Altered
Physical
The earliest form of this selection can be defined by
L………………..
in auditory and visual systems. Projections from attentional control systems appear to affect the
E………………………….
of cortical neurons
C…………………………….
the features of the stimuli.
Location
Excitability
Coding
These data inform us about the
S……………
(cortical versus subcortical, sensory cortex versus association cortex) where attention effects are
M……………………
during perceptual processing.
Sites
Manifest
To investigate the mechanisms of visuospatial attention, Hans-Jochen Heinze and their colleagues presented subjects with bilateral stimulus arrays oh
N…………………
symbols (two in each hemifield)
F…………………….
at a varying rate averaging about 2 per second.
Nonsense
Flashed
The researchers found the spatial attention led to activation in
E…………………..
cortex in the hemisphere contralateral to the attended side of the bilateral stimulus array, especially in the posterior
F………………. G………….
on the ventral cortical surface.
Extrastriate
Fusiform Gyrus
It was possible to show that the P1 attention effect and the PET attention effect in the posterior fusiform gyrus (extrastriate visual cortex) were
A……………………….
related.
Apparently
In an fMRI study of spatial attention, Roger Tootell and Anders Dale addressed questions about the details of the organization of attentional
M……………………….
in the visual cortex.
Modulations
The investigators performed careful retinotopic mapping of the subjects to reveal the
B………………..
of the early visual areas from
V… (primary visual cortex)
through V…..
and beyond.
Borders
V1
V4
These researchers found that spatial attention was represented by robust modulations of activity in
M……………… E………………………..
visual areas, as well a smaller modulation of
S……………………..
cortex.
Multiple Extrastriate
Striate
This work provides a high-resolution
V…………………
of the functional anatomy of multiple areas of extrastriate and striate cortex during sustained spatial attention in human visual cortex.
View
Attended stimuli produce
G………………
neural responses than do ignored stimuli, and this difference is observed in multiple visual cortical areas. What does attention do for the brain to permit the
A…………………….. S……………………
to exert a greater control on perception and awareness?
Greater
Attended Signal
John Duncan and Robert Desimonde proposed a
B…………………. C…………………………
model for selective attention.
Biased Competition
The idea is that different stimuli in a visual scene may fall within the receptive field of a
V…………… N………………..
creating a situation in which the two stimuli are
C……………………………..
to control the neuron’s firing. The biased competition model of attention suggests that attention can help
R……………………….
the competition in favor of the attended stimulus.
Visual Neuron
Competing
Resolve
In studies using fMRI, Sabine Kastner investigated this model for
S……………………..
attention.
Spatial
Kastner showed that, in the
A…………… of focused
spatial attention,
N…………….. stimuli,
when presented simultaneously, can
I……………………..
with one another (simultaneous condition), reducing the neural response evoked by each stimulus in comparison to when only one stimulus is presented
A………………….. (sequential condition).
Absence
Nearby
Interfere
Alone
When attention is introduced and
D………………….
to one stimulus in the array, the simultaneous presentation of the competing stimulus
N……….. L…………………………..
interferes.
Directed
No Longer
This reduction in interference can be
C…………………………………
as attention
A…………………………………
the influence of the distracter (the nearby ignored stimuli), which in this case would produce
I…………………………………..
in neuronal activity if attention did not intervene.
Conceptualized
Attenuating
Interference
Effects of attention might be manifest
P…………….
to cortical processing, which in vision means in the lateral
G…………………………….
nucleus of the
T……………………………….. (LGN).
Prior
Geniculate
Thalamus
Kastner and colleagues have addressed this question using high-resolution fMRI in humans. They
C…………………
subjects attend to the left or right half of bilateral arrays of
F……………………………..
checkerboard stimuli.
Cued
Flickering
These stimuli activated the LGN and multiple visual cortical areas, and these activations were
G…………………
in amplitude for the
A…………………..
arrays (e.g., left array) in the contralateral (e.g., right) LGN and visual cortex.
Greater
Attended
These studies demonstrate that
H…………………..
focused spatial attention can
M………………………
activity in the visual system in the
S……………………………
relay nuclei in the thalamus, thereby providing strong evidence for
E…………..-S…………………….
models of attention.
Highly
Modulate
Subcortical
Early-Selection
