 Hi, and welcome back to this video in the biological psychology video course in this video 6.2 We're going to take a look at attention Now what is attention attention is a selection process It's the selection of one thing over another and that one thing that can be anything it can be one aspect of visual input So if you have multiple things in front of you, you can co-pay attention to one thing and not the other things right visual attention You can also pay attention to a memory You have a lot of a lot of memories in your long-term memory that are not at any moment active if you if you Remember you activate one of these memories that you could say that that's a form of Internal attention where you select one memory over the other memories But it's a very different form of attention of course then visual attention where you visually pay attention to something You can also pay attention to a sound so imagine that you're at a party where a lot of people are having a Conversations then you generally are able with some effort to to pay attention to the person that you are talking to and more or less Ignoring all the disrupting conversation around you. So that would be a form of auditory attention Now and there are many many forms of attention that you can think of for example right now I'm also my attention is focused on my visual sense mostly and also my hearing because I'm listening to myself speak And I'm looking at myself also in the the screen of the camera And I'm not so much paying attention for example to the feeling of the carpet under my on under my feet All right, so then so this is a way to pay attention to one modality over the other modalities So Intention is not really one thing. There's not one process that is attention rather Selection is really a very important Part of all cognitive processes and we've already seen different forms of attention in different sections of this video course And attention is really an umbrella term that describes all these different forms of selection that are so important for us And for every cognitive process Now attention can be directed in space and in time So especially when we're talking about visual attention and we're going to take a look at a few famous paradigms So in a paradigm is basically one very stereotyped experiment psychology experiment For example the poshner queuing paradigm developed by the psychologist Michael poshner Visual search we won't take really take a look at it But visual search is a class of experiments in which participants have to search Visually for one item among a larger set of other items And we're also going to take a look at the so-called attentional blink paradigm Which is used to study a temporal forms of attention But let's start with the poshner queuing paradigm. It's a very very simple paradigm But I think it illustrates very well some key components of attention So the the task for the participant in this paradigm is to respond to the circle So the circle here is this is here at the bottom and the participant for example has to press the spacebar as soon as this circle appears Or for example indicate whether the circle is on the left or the right side Or maybe indicate the color of the circle the exact task doesn't really matter as long as the participant has to do something with that circle Now the location and that is important the location of the circle is predicted by this this arrow queued as you see here in the center So if the queue points towards the left as it is the case now The circle will also with 75 percent probability appear on the left and on 25 percent of the trials it will appear on the other side Now and then what happens is that if participants see the arrow queue then and they know that the arrow queue Predicts the location of the target. Of course, they will shift their attention to the queue side right the left side in this case Now what you then find is that participants make fewer errors and make faster Responses on validly queue trials so trials in which the target indeed appeared on the side predicted by the queue and more errors and slower responses on these other trials and This this shows very simply that we are able to voluntarily direct our attention to a location in space right because this arrow queue the this requires us to Interpret right what what this this queue means? It's an arrow that points to the left Once we've interpreted the meaning of this queue and we are aware that the queue predicts the location of the target then Voluntarily through an act of will we shift our attention to the left in this case and that is called Endogenous attention because the shift of attention is endogenous. It comes from within us right? So it shows one aspect of attention that we are able to exercise voluntary control over what we attend to to some to some degree There's a variation of this paradigm in which the queue does not predict the location of the target But it is simply a very salient event and that is what you see here So in this case the queue is this is this square and participants have to ignore the square and the location of the square also Does not predict where the circle is going to appear but the square is suddenly presented It is a salient visual event that automatically captures your attention, right? It's like a light that flashes and it automatically grabs your attention and Then what you find is that it's essentially the same pattern of results So if the the circle appears on the side of the queue the the square in this case Participants make fewer errors and they respond faster than when the circle appears on the other side in other words This this salient queue even though it is not relevant to the task at all It nevertheless captures the attention of the participants and affects their subsequent behavior namely the reporting of the target the circle And what this shows is that attention can be automatically captured, right? This is called exogenous attention because it is not doesn't really the shift of attention doesn't not come from within us But it is imposed upon upon us by the by the environment, right? in this case we have no voluntary control over the shift of attention and even what is more even if we want to ignore the The rectangle because we know for example that it disrupts our performance on this task Then you are not able to do so because it really automatically grabs your attention and you have very little control over that Right, so together these two paradigms showed it two properties very simple properties of attention a you often Voluntarily control what you would tend to but be you don't always Voluntarily control what you attend to right and that matches. I think very well how we intuitively feel That our attention is driven Now as I mentioned attention cannot only be directed in space as as we saw in the post-acqueuing paradigm But it can also be directed in time And in that case it means selecting one moment over another moment So in a very famous paradigm to test this is the so-called attentional blink paradigm And this is a bit of a strange paradigm So take a moment to bear with me and take a moment to think about the logic behind this paradigm and then it will become clear So how it works is that participants see a stream of very rapidly presented letters for example 100 milliseconds per letter So in this case that would mean the participants first see a cross in the center of the screen screen and that is matdx y I Now there are two targets that the participant has to has to report the first target in this case is the colored letter and The second target is an X which is present on 50% of the time of the trials So basically the participant sees all these letters right that flash by very rapidly and then we ask the participant Okay, what was the colored letter and the participant has to say in this case It was a T and did you see an X or not and in this case the participant would have to say yes I saw an X right and the T is the first target or the T1 as it is sometimes called and the X is the second target or the T2 Now so there are two targets and there is a crucial manipulation Namely the lag between the two targets So here you see that in between the T and the X or the first and the second target There is the D which is a distractor. It's an irrelevant letter So this we call a lag two because there is a displacement of two my two positions between the T and the X But on some trials there with these displacements will be longer and on some trials it will be shorter So we vary basically the distance in time between the first and the second target and then what you generally find is that Is the following pattern of results? If the T2 very rapidly follows the T1 attention is impaired and you can see this in this graph if you look at the green line So what you see here is on the X axis the lag So basically lag 3 means that the second target was presented three positions in time after the first target and on the Y axis You see the accuracy of reporting the second target. So saying whether there was an X or not given That participants reported the first target correctly And what you see is that basically there is a dip and this dip is called the attentional blink What this means is that if participants see the first target Then their attention gradually briefly shuts down, right? So at at lag 0 they see they see the first target and then they start processing that target And you essentially your attention shuts down blinks and as your attention starts to blink You become progressively worse in detecting the second target and the worst performance in this particular experiment was at lag 3 So and then after like three your attention kind of opens up and you go back to the original performance again If you compare that to a control condition Right, so here we see selection in time because at time zero participants see the first target They're selecting that that goes at the expense of the second target if it is presented Shortly after the first target the attentional blink. So it's a clear demonstration of selection in time And of course, this is compared to a control condition indicated in orange here where there was only a t2 Right, so whether there was only an X present or not And this shows as I already said a few times a lapse or blink of attention in time Tensional blink Now now that we've looked at these basic forms of attention right spatial attention as shown by the post-necuing paradigm and Temporal attention as shown by the attentional blink paradigm visual attention in both cases Let's take a look at how we can explain some aspects of attention from a neuro biological perspective Now we're going to take a look at the biased competition theory Which explains how explains some aspects of attention especially visual attention and this theory is a very elegant theory That was proposed by John Duncan who we've already seen During the the second lecture on neurons and brain anatomy when I recommend his book how intelligence happens Right. So as I mentioned, then he's very big name in the field John Duncan Now the idea of biased competition is that stimuli compete for neural representation and that attention determines which stimulus wins the competition Now that sounds kind of abstract, but we can make it more concrete with the view a few examples And this has been studied mostly for visual attention But I think the the the the ideas behind biased competition are also applicable to different forms of attention But here we're going to take a look at visual attention and I should emphasize that biased competition is just one model of Of attention and there are different models of attention that describe different Aspects of attention because as I said the tension is not really one thing It is a collection of cognitive processes that is described by many different models, of course But here I think biased competition is quite elegant and quite a nice example So imagine a neural That responds to only one part of the visual field and we call that the neurons receptive field And we've already seen the concept of a receptive field in the the perception section So what it means basically is that we have this neural here and this neural only looks you could say at this part of The world indicated by the circle. He's only interested in things that appear within this this part of the world That's its receptive field. So the neuron is selective in space The neuron is also selective in what it responds to it is actually you could say a simple cell that we've met in the perception section And it responds only to rightward tilted line segments Now so you see if there's this rightward tilted line segment the activity bar is full It's completely red. So this neuron starts to fire very highly strongly If a leftward tilted line segment is presented in its receptive field Then that is a non preferred stimulus for this neuron and the neuron does not really respond to it So the activity is low Right now what happens now if we present both a preferred stimulus So the rightward tilted line segment and a non preferred stimulus the leftward tilted line segment in its receptive field You might think that the activities add up right so that the neuron starts to fire even more Right with the sum of the the activities that each stimulus elicits on its own, but that's not the case Activities intermediate and it is not the sum of the the two activities Rather it is kind of the average approximately So what is happening is essentially that the presence of the non preferred line segments Drives the response of the neuron to the preferred line segment down Right, so it reduces the response to the preferred line segment line segment and conversely the presence of the preferred line segment Increases the response of the neuron to the non preferred line segment you could say so there the two stimuli are kind of mutually Inhibitory and the result is that the neuron starts to fire with an intermediate firing rate as indicated here in this in this bar But attention can change this and that is the key tenet of biased competition So if we attend to the rightward tilted line segment to the preferred stimulus then The activity goes up and this means in a sense that the preferred stimulus is represented and the non preferred stimulus is ignored In other words the neuron starts to fire fully as though only the rightward tilted line segment We're present in its receptive field right and the non preferred line segment is completely ignored in other words The preferred line segment has won the competition Conversely if we attend to the non preferred stimulus then activity goes down Meaning that the preferred stimulus is ignored Right and the non preferred stimulus is represented in other words If we covertly attend to the non preferred line segment the leftward tilted line segment The neuron responds as though only this leftward tilted line segment were present in its receptive field and the other preferred stimulus is ignored Right you could also say and I think that's an important point that the non firing of this neuron is a way for this neuron to Represent the presence of a non preferred stimulus right not firing is just as legitimate a way to represent something as firing is So to summarize biased competition when multiple stimuli are shown attention determines which stimulus wins right which stimulus drives neural activity and The other stimuli that are not attended are ignored and I have a very nice picture here. I'm not sure why I chose chose that animal Okay, now with that let's move on to the next video video 6.3 in which we're going to talk about consciousness