Attention I: Effects on stimulus processing

Question 1

What did William James say about attention?

Answer 1

talking about stuff in the environment and the idea u can move attention in space to seize an object and can talk about theories of attention that go beyond that and how do you keep track of talking simultaneously
-focalization, concentration, and consciousness are its essence - attention is consciousness and is the withdrawal of some things

Question 2

What are two questions to consider when measuring covert attention?

Answer 2

-how early does it start? - how far down does it go?

Question 3

What is automaticity?

Answer 3

when we ask you to ignore something and see responses to thing we asked you to ignore - when attentional experience fails you to perceive something but is processed by some other part of the brain later

Question 4

What is exogenous or overt attention?

Answer 4

-externally driven attention - eye movements are overt shift of attention

Question 5

What do model of visual saliency do a good job of predicting?

Answer 5

-models of visual saliency do an excellent job of predicting where we will move our eyes based on image features like brightness contrast color and movement
-contrast in color will attract attention

Question 6

What is endogenous or covert attention?

Answer 6

internally generated shifts in attention like if you are told to look at the middle of a screen -how attention moves around in space without changing your field of view so perceptual representations are retinotopic so need to make sure we know what region in space corresponds to what part of the retina

Question 7

What study was done to capture covert attention by exogenous cues? What were the results?

Answer 7

-the first cue occurs on the same side as the target half the time and on the opposite side half the time (this was done to prevent response preparation)
-paricipants are instructed to keep their eyes focused on the center of the screen and push a button to the second of two simple images

RESULTS
-when the target occurs shortly after the cue responses to the target are faster
-this is true even when people do not move their eyes
-demonstrations of this sort were critical to establishing covert orientation of attention is a real thing
- - lower scores mean you reposing quickly and if target occurs shortly after the cue the cue location has an advantage only for a couple of ms like 300ms and then the uncued location picks up so after 300ms you are faster at responding to the cue location

Question 8

In the study to capture covert attention by exogenous cues, what was seen if the delay between the cue and target is too long (more than 300ms)?

Answer 8

-the effect reverses - this is called inhibition of return - the response is slower to the cued location than uncued location

Question 9

What does inhibition of return suggest? What does it suggest evolutionarily?

Answer 9

-suggests that - attention shifts back to the fixation point within about 300ms and
-recently attended locations are temporarily inhibited
-if looking at fruits of different colors evolutionarily if your attention gos back to the same spot you already looked at then your search is less efficent and this is why you are less likely to return your attention to places you have already seen

Question 10

What was done in the study to capture endogenous attention using endogenous cues? Unlike exogenous cues they are typically very likely or 80% to be valid why?

Answer 10

-participants are given a symbolic cue to the location of the target
-because in this case we want to see yow you strategically shift your attention based on task goals (if you made it 50/50 you would stop paying attention to the endogneous cues)

Question 11

What were the results of the study to capture endogenous attention using endogenous cues?

Answer 11

-responses to validly cued trials are faster than trials with a neutral cue
-the infrequent invalid trials also incur a cost

Question 12

How does endogenous attention have different temporal dynamics compared to exogenous attention?

Answer 12

-after 300ms exogenous cuing produces inhibition
-but endogenous cuing requires 300ms to show a facilitatory effect
-so there seem to be separable processes underlying these two deceptively simple effects

Question 13

Can endogneous shifting be sustained for long periods of time?

Answer 13

yes - can sustain somehting for minutes or hours to the exclusion of other phenomenon
-exogenous cuing not the same - over quickly

Question 14

What is the classic cocktail party experiment?

Answer 14

-participants are instructed to attend to one ear and ignore the other
-to provide an overt measure of performance and to make the attentional task more challenging participants are asked to shadow (repeat in real time what is being said) the attended ear
-after the experiment participants had no memory of the unattended stream
-are more salient to certain information in unattended stream like your name

Question 15

What did cherry say about the language of the rejected ear unrecognized?

Answer 15

-in a further set of tests the two messages one for the right ear and one for the left started in english - basically the participant could not tell if in the unattended ear the language was german or english - this means the unattended input is not being processed very deeply

-HOWEVER - if someone calls your name in the unattended channel you are likely to pick it up meaning there is some semantic processing occuring

Question 16

What is a limitation of behavioral approached for attention?

Answer 16

-we do not know what is the process between hearing and recall
-have to ask afterwards what do you remember about and what you heard and there are all kinds of stuff happening between hearing and recall so there are memory phenomenon like encoding meaning did u transform what u heard of the literal sound waves hitting your ear into some other representation did your recognize the words did you understand things in real time in order to recall things later you have to store them and are able to comprehend them and threw it away

Question 17

What are some processes that are in the black box between hearing and recall?

Answer 17

encoding
comprehension
storage
retrieval
basically memory
interpretation (recall vs reconstruction)
-behavioral really difficult to demonstrate someone did not hear something

Question 18

If attention is in William James’s terms a taking possession by the mind of one out of several simultaneously possible objects how early does this happen? And how thoroughly ignored are those things we don’t take possession of?

Answer 18

-by early we mean both in time and in terms of where in the processing stream the selection is occurring

Question 19

What is early selection?

Answer 19

-can enhance the earliest response to a particular stimulus and can also temporarily change the way the brain responds to a stimulus this is consistent with early selection

1. incoming stimuli
2. extraction of physical properties
3. filter (dial)
4. extraction of abstract properties

Question 20

What is late selection?

Answer 20

-second example is late selection so extract properties and enhance the salience internally for parts of the stimulus so interpret anything and are automatically processing everything coming in
-process what u can and based on working memory processes i will enhance some things and inhibit others
1. incoming stimuli
2. extraction of all properties
3. availability for report - short term memory

Question 21

How can physiology help us find the answer between early and late selection?

Answer 21

in one famous example corteen and dunn conditioned people by pairing electric shock with certain words so that when these words were heard people would exhibit a galvanic skin response - after conditioning these words would still produce some detectable gsr even when played among words in the none shadowed ear during selective shadowing of words on the other ear - when presented a conditioned word to which they have to make an overt response - they miss critical words presented in the nonshadowed ear yet still show some gsr to them
-gsrs for unattended words were claimed to generalize to synonyms of the conditioned words which would seem to imply some processing of their meaning - exactly the kind of processing which filter theory prohibited for unattended words
-gsrs also conditioned to synonyms of the words which seems to process some meaning which means filtered theory prohibited for unattended ear

Question 22

What do erps provide a window into?

Answer 22

-early sensory processing
-eeg has a very high temporal resolution but poor spatial resolution
-when we look at erps we are looking at averafes over many typically at least 100 responses

Question 23

Where do auditory erps have structure?

Answer 23

at multiple time and amplitude scales
-at the less than 10ms time scale we can resolve low amplitude wave attributed to the brainstem
-the first few tens of ms post stimulus are dominated by activity in the early auditory cortex
-event related potenitals continue to evolve for hundreds of ms post stimulus

Question 24

In auditory erps, at the less than 10ms time scae what can we resolve?

Answer 24

-low amplitude waves related to the the brainstem

Question 25

In auditory erps, the first few ten ms post stimulus (20-50ms) are dominated by activity where?

Answer 25

activity in the early cortex
- seen an N1 and the N170

Question 26

In auditory erps, event related potentials continue to evolve for how many ms post stimulus?

Answer 26

hundreds of ms post stimulus - there is some less organization tho post 300ms

Question 27

What did the classic experiments by Hilyard and colleagues explore? What was the critical measure for the experiment? What were their overall goals of the study?

Answer 27

how we can tune in to spatially separated auditory streams
-participants listen for quieter tone in one or the other stream
-the critical measure is the erp to tones in the attended and unattended stream

Goals: to what extent is the response in the stimulus in the attended ear enhanced and when in time is that happening and using a forward probabilitiy model in the brain is that happening

Question 28

What is the cocktail party experiment fallibility that Hilyard and colleagues wanted to remove?

Answer 28

it is difficult to shadow someones speaking so they decided to do a tone version where one is quieter than one and only monitor one ear with two channels - the tones are short so we dont respond to the same stimulus over and over

Question 29

What were the findings of Hilyard and colleagues study with erp and the two channel tone study? What selection of attention did their results support?

Answer 29

the N1 negative wave peaking around 100ms is greatly enhanced by attention
-this suggests that attention can modify quite early cortical processing of sounds
-In the attended ear the response is more than the unattended very early on in auditory processing this results in increased response to the attending ear so the idea is the early selection of the attention

SUPPORTS- EARLY SELECTION OF ATTENTION

Question 30

Does attention impact the brainstem evoked responses observed in the first few ms post stimulus?

Answer 30

no - this does not have a difference in the brainstem in teh first few ms and all the way down I in the brainstem so this affect of attending one ear to another is not that top down - can decode what someone is into depending on their brainstem responses

Question 31

Where are attentional effects seen in the erp tone study by hilyard and colleagues?

Answer 31

-there are attentional affects before the N1 however in the P20-P50 complex
-this complex is thought to be generated in primary auditory cortex based on other studies combining scalp eeg with intracortical measures

Question 32

Where in the brain is the P20-P50 complex arise from which comes before the N1?

Answer 32

the primary auditory cortex - this was seen via eeg and meg

Question 33

What does the attentional difference wave graph of attended minus unattended show?

Answer 33

Seeing first 50ms of the response so what they re showing is instead of showing unattended ear versus attended ear they are showing difference between left ear and right ear and have subtracted the two waves from each other and would get a smaller version of the attended line for each ear which they plotted there is a difference between stimuli at 100ms and is more negative in attended ear than unattended ear and at 20-50ms and the response is more positive in the attended ear than the unattended ear so the p20-50 response is stronger in the attended ear - 20ms post stimulus is very fast and where in the auditory system is this happening so is this the early auditory system we know this is not in the brainstem and it turns out from meg the p20-50 response is coming from A1 - have analogous studies in the visual system

Question 34

What was done in the study investigation visual attention to spatial locations and V1? What were the results of the study

Answer 34

participants had to determine the orientation of a T against a background of plus signs in the cued visual field
-have a classic endogenous attentional cue in the visual field so get an arrow which is the right screen and dot where you maintain focus and use an eye tracker to make sure you do not move eyes from that location and have two patches which occur in the upper visual field and are matched for contrast they have and your job is to determine whether the t is upright or not so those two visual patched will encode activity in the visual field - there is a stronger response because there is a difference between the attended and unattended location
-greater activity was observed in the ventral contralateral visual cortex down to v1 indicating attention effects on the earliest site of cortical processing (have an enhanced response to the left visual cortex so have the attended right condition and the attendee left condition and top is a segmentation of the visual cortex and the ventral portion of v1 and can see v2 and the stimulus is the upper visual field - where there is an enhanced repose to the attended versus unattended stimulus so there is a stringer response when attending to right over left)

Question 35

Even though activity in early processing areas is influenced by attention what can fmri not tell us? What could this activity be linked to? What can we used to provide an index of the earliest time of activity?

Answer 35

-how early this effect is in time
-can be due to re-enterant activity - feedback from later visual areas after the first feedforward response
-eeg provides an index of the earliest in time v1 activity called the c1

Question 36

What is the C1?

Answer 36

-eeg provides an index of the earliest in time v1 activity called the c1
-the c1 is a negative going wave when measured at this electrode at the center of the head and is measured when attending to a location

Question 37

What did EEG data from Noesselt et al experiment show about the affect of attention on C1? What was seen?

Answer 37

there is no effect of attention on c1 - the earliest in time observed was on the p1 a slightly later response thought to originate from areas lateral and ventral to v1 (contralateral)
-Attending top the right enhances positive response on left hemisphere and negative repose on right hemisphere is the response in contralateral hemisphere to visual field is stringer

Question 38

What do the finings from the eeg studies mean for early selection in visual and auditory stimulus processing?

Answer 38

-there are very early effects of attention in the primary auditory cortes and somewhat later in the visual cortex
-recall that a1 is later in the auditory system than v1 is in the visual system (there are more synapses between the cochlea and A1 and the retina and V1)
-attention does not seem to work like a strict filter - responses to unattended stimuli are attenuated not abolished

Question 39

What was found in studies investigating attention and target selection aka a two channel study where you monitor for the quieter stimulus or tone?

Answer 39

-in monitoring experiments there are also attentional effects related to late selection the P300 response to targets
-this effect is attention dependent in ways that early responses are not - in some cases no p300 is observed to the unattended channel

Question 40

What is the attentional blink and how is it related to late selection?

Answer 40

so when they attentional blink your eyes are wide open did not blink but your attentional system was distracted by one target so when the other target appeared you didn’t register it so it is like you blinked - when there are two targets the relative thing of the first target can help you determine a signal - comparison condition is look for an r or a c or an r and a c
-phenonomeically its like you dont see the second probe 300ms after the presentation of the first if it is presented then

Question 41

Even though erps are fast how long do they continue?

Answer 41

for several hundred ms post stimulus

Question 42

What is the rapid serial presentation rate?

Answer 42

that rapid serial visual presentation are presented very quickly (here there are 33ms/stimulus, ISI of 50ms; 12 stimuli per second)

Question 43

How can the erp continuation post stimulus interference with rapid serial visual presentation be fixed?

Answer 43

via subtraction of probe absent trails from probe present trials to help resolve this issue (similar to deconvolution in fmri)

Question 44

What were the results of the blink study?

Answer 44

Lag 1 lag 3 and lag 7 are the same so the visual evoked response to these stimuli are more or less identical whether or not you registered you saw it
-despite a pronounced blink in the behavior no differences were observed in the early portion of the visual response whcih means even though you feel like you did not see it you had normal responses atleast a few synapses beyond v1

Question 45

What is the relationship between the attentional blink and the n400?

Answer 45

-the n400 is a response to various kinds of anomalies
-n400 is discovered by highly predicting sentences so responses to tings that are unexpected - in order to get this effect you must be processing the word to an extent to see if this is a word I predicted our not
-unrelated words produce a larger n400
Fill up the row so they are the same lenght and teh single target condition is say if stimuli is related or not so people are pretty accurate at 92% and was very good for speed of stimuli - when critical stimulus occurs after the first atget still good when stimulus occur down at lag 7 pretty good - at lag3 accuracy drops to 65% which is basically like 50/50 chance so just like the response you get an attentional blink for some reason
-the n400 showed no obvious effect of lag despite huge diffreneces in accuracy so whatever is happening during an attentional blink is not preventing word recognition from processeing far enough to produce effects of semantic relatedness
-participants had to monitor also for a number and also whether the white letter was an e or not and this was nearly impossible at lag 3

Question 46

What did the n400 experiment demonstrate?

Answer 46

word processing is intact even when the target does not make it into working memory

Question 47

What is the relation between p300 and lag 3?

Answer 47

-the p300 is strongly attenuated by dual target instructions to begin with
-there is large effect of lag and at lag 3 there is no p300
-the p300 is indexing something about explicit processing of a stimulus

Question 48

What does the p300 represent and the n400 represent?

Answer 48

n400 - semantic integration
p300 - updating of working memory
-the word processing that leads to the n400 does not seem to require and awareness whereas cognitive process marked by p300 needs you to be aware and store the target - at lag3 too busy updating working memory so do not update it

Talking about autonomous perceptual processes which n400 is smectic integration which happens outside your explicit control for the most part there are times where it is fairly effortful to understand what someone is saying and most of the time how they are related to one another is fairly obvious people can unconsciously predict what happens next without even integrating it - this happens even when a word occurs subconsciously - the p300 its going to index a reflection of updating the reworking memory so that entry of the working memory has a fixed time course so if you see two stimuli one after another youbcan put it into the working memory but at some pint you are busy to put stimuli one in working memory that at lag 3 you dont update it