Attention Flashcards
What is attention?
Given limited capacity to process competing options, attentional mechanisms select, modulate, and sustain focus on information most relevant for behavior.
Focus on information most relevant to your goal
What is the problem solved by attention?
How to allocate limited resources (energy & time) in the service of behavior
What is the importance of attention
We need to prioritize information so we do not waste time and energy on irrelevant efforts
Challenge of attention
How to balance the need for selective focus with the need to handle new situations as they arise
What are the possible sources of attention? And what is it?
Exogenous
Endogenous
The “cause” for directing one’s attention
What is a exogenous source of attention?
in the environment, reflexive, automatic, “bottom-up”
A salient stimulus, e.g.: a loud clap, a sharp pain, a bright flash, a sudden movement
Pulls your attention to it
What is an endogenous source of attention
in the mind, voluntary, intentional, “top- down”
A desire, goal, or instruction, e.g.:
What are they talking about?
“What is in the room behind that window?”
Is this the correct exit from the highway?
She told me to focus on the guy in the yellow shirt
What are the possible targets of attention? And what is it?
External
Internal
What you are attending to
What is an external target of attention
sensory information, in the environment
A sensory modality, spatial location, feature, or object, e.g.:
The sounds of the forest
The back of the classroom
The orange shirts of the opposing team
The doughnut in the display case
What is an internal target of attention?
mental representations, in the mind
A memory, imagery, or plan, e.g.:
The license plate number of a hit and run driver
You and your significant other relaxing on a tropical island
The next step in a recipe you are cooking
What is overt attention?
Involves actual movement of the sensory surface
E.g: moving the eyes, directing the ear
What is covert attention?
Does not involve actual movement but you ares till shifting your attention,
e.g.: “looking out the corner of your eye”, “eavesdropping on a conversation at the next table”
What is transient attention?
Momentary focus on something, e.g.: glancing at a stranger’s face
Milliseconds
What is sustained attention
Prolonged focus on something, e.g.: standing watch at a door for 2 hours
Minutes
What is selective attention?
Focus on one thing to the exclusion of others, e.g.: watching TV so intently, you don’t notice your friend enter the room
What is divided attention?
Try to focus on multiple things simultaneously, e.g.: talking on the cellphone while driving a car
Example: At the zoo, after reading a sign that says “Squirrel monkeys like to rest on tree limbs,” you look up at the top of a tree in the monkey house for several minutes.
What are the sources, targets, and types of attention?
Endogenous and external
Overt, sustained and selective attention
What is the cocktail party affect
Focus attention on a specific person when there is lots going on
State all the steps in the hierarchy given to determine when attention selection occurs
What is lower perceptual analysis
V1 for example
What is higher level semantic analysis
Where we prices for meaning
What did the dichotic listening experiment do and what were they used for?
Used for determining when does attentional selection occur
Play sound in each ear
Used shadowing → repeat word for word the message you hear in one ear
“Attend to the left ear”
What are the source, targets and types of attention involved in dichotic listing
Source: endogenous
“Attend to the left ear”
Target: external
Sounds entering ear
Covert: can’t tell which ear they are attending to
Sustained: have to keep attending to left ear for an extending period of time
Selective: have to attending to only one ear
What is the early all-or-none filtering model (Broadbent’s filter model) and what experiments support that?
Attention acts of a filter after low-level perceptual analysis
Unattattened messages didn’t make it through at all
Cherry
Cherry findings for dichotic listing
Could report existence of message
Could report gender of speaker
Could not report content
What is the early attenuating model (Treisman’s attenuation theory)? and what experiments support it?
Filter occurs after low-level perceptual analysis but it is not a all or none filter
If the unattended message is meaningful then it gets through and getting processed
Moray (1959)
Gray and Weddeburn (1960)
What did the dichotic listing study by Moray find
Could report change in gender of speaker
Could report change in pitch of a tone
Could NOT report a word repeated 35 times!
Could report hearing own name in unattended message! → raised problem for all or none filter model
What did the dichotic listening study by ray and Weddeburn (1960) find and do>
For one word the message would flip ears then flip back
Left ear hears: “Dear 7 Jane”
Right ear hears: “9 Aunt 6”
“Dear Aunt Jane”
Meaning of unattended words being taken into account! –> problem for all or none filtering model
What is the late selection model in attention? and what experiments support it?
filter is after the unattended message has been processes for meaning (high-level semantic analysis)
Even if they aren’t consciously aware of the unattended message the brain has the meaning of the information available
McKay
What did the dichotic listening study by McKay find
Meaning of biasing word (“river” or “money”) in unattended ear affected participants’ choice
However, participants were unaware of the biasing words!
What is the modern interpretation of where attentional selection occurs?
Strategic control of attention
Attention is not a single filter at a single location in processing → we can strategically allocate attention very early or later depending on the nature of the task, our goals, etc.
attention is determined by top-down modulation (executive/cognitive control) → allocate attention at different levels of processing as needed
What is an ERP?
Event-related potentials
Activity of the brain
Average of EEG signal
How are ERPs measured
take EEG recording and chop out individual responses and average them
Time-locked to event of
interest
Typically plotted with negative up!
What is an EGG and what does it measure? Is the temporal resolution or spatial resolution good?
Non-invasive technique
Measures surface electric fields generated by post-synaptic potentials in dendrites of neurons
High temporal resolution: >1000/sec can be measured almost instantly
Low spatial resolution: measures up to 256 electrodes → don’t know exactly where the signal is coming from
Electric fields spread out through space → don’t know where the source is
How do they determine what location on the scalp to put the electrodes for EEG
Standardized names for different location where electrodes are placed on the scalp
How are the electric fields created by neurons enough to measure with EGG?
We have lots of pyramidal cells and they all have long apical dendrites
Because all of the apical dendrites are inline → they all generate electric fields that are aligned → generate electric field large enough to be measured
How can we determine ERP over time?
plot data for many electrodes over time → measure strength of the electric field
Show surface distribution
What are the three stages of ERPs to audio evoked responses? And it what time frames do they occur? when do the peaks increase?
Brainstem reponses: first 10 ms
Midlatency responses (primary auditory cortex) –> 10-50 ms
Late waves (secondary/tertiary auditory cortex) –> first 500 ms
Peaks are greatest in the late waves
What is the attentional stream paradigm?
m: When do we see the effects of attention on these brain signal
Random sequence of auditory “pips” played for participan
Occasional deviant targets (different volume or pitch)
Instructed to attend to one ear
Compare ERP from attending ear to the unattending ear
Does attention have an effect on brainstem evoked auditory ERPs? What about mid latency potentials? What about late waves? How do they plot it?
No effect of attention on brainstem evoked potentials
Had effect on mid latency potenitals
Had an even larger effect on late waves
Plot the difference between attended and unattended ear
Does the brain respond differently to the standard beeps compared to the oddball beeps when measuring auditory ERPs? does this also occur in the unattended ear?
around 200 ms → difference between deviant and standard beeps –> late waves
Even unattended differences between the normal and oddball beeps are detected
Where do the mid latency potentials occur for auditory ERPs
Primary auditory cortex
Where do the late waves occur for auditory ERPs
secondary and tertiary auditory cortex
What is the Posner orienting task?
Staring at fixation dot and you get a cue → either an arrow to the left, arrow to the right, or both ways → tells you where the stimulus is most likely to appear
Spatially cued trials
80% valid
20% invalid
Neutral trials → No spatial cue
What is the source, target, and type of attention in the posner orienting task with the arrows?
Source: endogenous → gives a suggestion
Target: external → location on screen
Covert → you have to keep your eyes fixated on the central dot
Transient → is quick
Selective → You know that more often than not it appears on the proper side but you better be ready for the other side
Is the valid, neutral or invalid trial responses fastest in the endogenous posters orienting task
Valid < Neutral < Invalid
What is the posters originating task for an exogenous source
the cue is a box → pulls your attention over to it → box goes away and stimulus appears
What does the Posner orienting task with exogenous source depend on?
Effect depends on the length of the delay between the cue and the target stimulus
What happens at At short cue-to-target intervals (<= 100 ms) in the Posner orienting task with an exogenous source?
People are faster to respond to a valid cued stimulus → similar to the endogenous
What happens at At long cue-to-target intervals (>= 300 ms) in the Posner orienting task with an exogenous source?
Now people are faster to respond to invalidly cued targets –> different from endogenous
Reversal of the pattern → inhibition of return
Brain masks it as uninteresting
What happens in the posner orienting task with objects
Is the posner orienting task with objects exogenous or endogenous
Exogenous
Where would participants respond to a stimulus the fastest at
A < B < C
What did the posner orienting task with objects show
Attention can be allocated to objects not just spatial location
and being on the same object matters
What does neural correlates of attention mean
What is going on in the brain related to attention
What is the visual attention stream paradigm and how does it work?
Focus on the central fixation point → told to covertly attend to left of right side of the screen → stimulus appears on that side of other side
Can compare brain response to the same stimulus when it is being attended to or not attended to
What is the visual attention stream paradigm similar to
Similar to spatial cueing but w/sustained attention
Results of visual attentional stream paradigm
Boost in the response to this stimulus due to attention
What does the timing of visual attentional show?
Attention impacts the initial processing and the reentrant activity → looping → V1 processes the stimulus and it goes up to higher level areas but there are connections back down → activity from higher level areas back down → also gets affected by attention
Initial peak around 100 ms (positive peak) then you get a second peak in the same area (negative peak)
What is better than EEG for figuring out where things are happening
fMRI but it is not good at showing timing
Do we see different brain responses in V1,V2,V3,V4 to an attended stimulus vs an unattended stimulus
Yes
When do the affects of attention start
Early in primary cortex (V1/A1) and continue on
Can visual attention have effects on the LGN? can you see differences between the attended and unattended stimulus
Yes
Even differences between attended and unattended in LGN of the thalamus
Does attention have an effect on individual neurons
yes
With the experiment looking at V4 neurons and visual attention, what did we find?
Fewer AP by the neuron to the same stimulus when it is unattended compared to when it s attended
confirms attention is boosting neural response at the level of single neurons
What does this mean: Attention causes gain (multiplicative scaling), but no change in feature selectivity
The neuron does not respond more to every stimulus
Attention is boosting how strongly the neuron respond to only the specific types of stimuli it “likes”
What does this mean: Attention enhances signal-to-noise ratio and how is it tested
Helps neuron better distinguished when there is a signal there or not
Compare the response of an attended vs unattended stimulus —> starting from no stimulus to a faint stimulus to a higher contrast stimulus to a very high contrast stimulus
What did we find about signal to noise ration involving no stimulus
Small change due to attention and a small response in general
What did we find about signal to noise ration involving a medium/subs threshold stimulus
There is a large effect of attention –> like a spot light
And a general medium response
What did we find about signal to noise ration involving a high contrast threshold
There is a small effect/change between attended and unattended
And an overall big response
Can we have higher level visual attention to objects
yes
What is an example of higher level visual attention
Activity in Fusiform face area (FFA):
What does activity in the Fusiform face area (FFA show and what stream does it follow
In ventral stream
Response is greater when the participant is attending to faces compared to scenes
You can attend specific objects not just location
How did we determine that attention causes synchronization between brain areas
Recording local field potentials (LFPs) in V1 & V4
Present 2 stimuli –> blue and yellow ball
Cue tells them what stimulus to focus on
Change appears in one of the stimulus
Stimulus 1 activates V1a and V4
Stimulus 2 activates V1b and V4
When are are attending to stimulus 1 → areas V1a and V4 become synchronized
When you are attending stimulus 2 → V1b and V4 are synchronized
What did the synchronization experiments find
When the animal is not attending to that stimulus → both areas are active but out of phase
Attention to a stimulus increases synchronization between brain areas representing that stimulus
What do V4 neurons respond to
Colour and aspects of shape
How do we determine that 2 senses are related to the same objects
Example: how would we know that a ball is red and round
Synchronization
What are all of the effects of attentions
Attention affects reaction time, accuracy, and awareness of sensory stimuli
Attention can have effects less than 100 ms after stimulus onset → early
Auditory → 20-50 ms
Attention modulates neural activity in brain areas for locations and objects
Boost brain activity in parts of the brain that represent objects or locations in the visual field
Attention enhances neural response to attended stimuli (e.g. enhanced signal-to-noise ratio)
Attention increases neural synchronization between brain areas
What is Unilateral (hemispatial) neglect
A deficit in perceiving & responding to stimulation contralateral to damaged hemisphere
deficit of attention
Damage to what part of the brain is most common with Unilateral (hemispatial) neglect?
Damage to right parietal lobe leads to left side neglect
Is neglect a sensory or motor problem and why or why not
no
It’s not that you can’t see it → you just fail to pay attention it to
What would people with unilateral neglect do if you asked them to copy down a picture of a flower?
They would draw half
What would people with unilateral neglect do if you asked them to draw a clock from memory?
They would draw half of a clock
What would happen if you asked people with unilateral neglect to mark the center of a line
They wouldn’t mark the center
What is the piazza del duoma experiment and what did they do>
Case study → brought in patient with left hemispatial neglect
Asked participant to image they were standing at the sound end of the piazza looking north (A) → describe what they see (a)
Later they asked the participant image they were standing at the north end looking south (B) → describe what they see (b)
They would only describe things to the right side
What you have neglect in visual imagery from memory
yes
What did the piazza del duoma experiment show
Neglect in visual imagery from memory
What references frames can neglect occur in
Spatial
e.g. neglect of left side of space
Location-based attention
Crossing off the lines
Object-based
e.g. neglect of left side of objects
Drawing half a Flower
Object-based attention
Can you neglect stuff relative to body or visual frame of reference?
yes
Tilting your hea
What are the frontal eye fields involved in
Show similar effects to attention
How did they test the role of the frontal eye fields in attention
Target of saccade (movement) evoked in FEF = receptive field of neuron recorded in V4
They identified neurons in V4 whose respective fields where in a particular location in the visual field → found area in frontal eye fields that was involved in moving eyes to that particular visual field
Recorded the activity of V4 when FEF were stimulated
What did they find from the frontal eye field experiments
FEF stimulation enhances V4 response only when stimulus occurs in V4 receptive field
When there is a stimulus in the receptive field and the FEF are stimulated → even more response (in left picture)
FEF activation may be an enhancement of attention
What is change blindness
Changes in a picture or scene over time are not immediately apparent if not attended to
What is the flicker paradigm
demonstrated change blindness
Presented a photo then there is a brief mask, then there is a second copy of the photo where something has changed → then is masked and goes back to the first photo
What is the source, target, and types of attention used in the flicker paradigm
Endogenous and external
Endogenous because the change is not grabbing your attention → you are choosing to look for it
Overt → moving your eyes around to look for it
Transient → moving your attention from item to item
Selective → you have to look around at different things
Can change blindness occur in real life and why would it occur?
Yes
Occurs because there is a cost to focusing attention on something → we only represent features that are important to understanding the citation
Brain doesn’t have enough resources to pay attention to everything
Our brain just assumes things are the same
What is a dangerous example of change blindness
Forgets to see brake lights
