Alrighty, so where are we? Well we've followed visual information as it came in through the eyes, in through the retina ultimately back to the brain. we've talked about that interesting perception process of perception. You know, going from this raw sensory input to some sort of internal representation whereby what we see is actually objects, not just shades of light. and not only do we recognize the objects ,but we also get a very good idea of where they are in relation to each other. and so you know, now let's imagine that happening say with all five senses at once. Because at any given time, you are getting stimulation from all five and from, in fact, six, that proprioception we talked about, a sense of where your body is. We're getting input from all of that all of the time. Now, here's the interesting issue when it comes to humans. We cannot simultaneously perceive information from all senses at the same time. In fact, it seems like we cannot even simultaneously perceive all information, for one sense at the same time. So even vision, if we think about vision and stick with vision, look at all the things that are around you at any time. But as you look at all the things that are around you, notice that really you're only looking at one thing at a time. You're only consciously perceiving one thing at a time. Yeah, there's other things in the periphery, but we literally have this feeling of moving our attention around, and what that's about is selection. Selecting certain, in that case, visual stimuli to preferentially process and that's, you know, why do we have to do this? It just seems to be, you know, a limitation in our system. It would probably be really advantageous, if we could process all of the information really richly. But we just can't. So, how do we do this selection and what happens to the information that we don't select? That's the topic for today. So, here we are, week three, lecture six Selection. The first thing I want you to do just to kind of introduce the topic to you, is to follow this link and just follow the instructions of the video, and then come on back. All right, so go from there. Alright, welcome back. Well I don't know if that worked for you it works for a lot of people. maybe we can try to get some sort of pole up. To get a sense of how many people actually fail to see the gorilla. it is kind of startling, if you're one of those people, if you just didn't notice that gorilla coming in and pounding on it's chest. And then you watch again, and you see it, you are left with this feeling like, wow, how could I have missed that? and it really does show you how really efficient our selective attentional system is. We can really lock on to one thing. And at least seems as though the other information is not being perceived. Okay, so now let's go into the experimental analysis of that. A lot of this traces back to a scientist named Cherry who talked a lot about something he called the cocktail party phenomenon. And the idea here was he was, he was kind of interested in the fact that you could find yourself at a party. Like this with a bunch of other individuals and a bunch of little conversations going on simultaneously. One here. One here. Just a small one over here. This guy's talking to nobody. A group over here. A small conversation here. all these conversations, we seem relatively able, let's image this person here, relatively able to attend to the people in our conversation. While locking out the other conversations. So, this is a selective attention kind of context, an auditory selective attention context. But what Cherry noticed, is it seemed to him, that you know, let's say this was Cherry and he was talking with this women. Well if these people mentioned his name let's say, it felt like he noticed that. So he had this sense that really, to some extent, we're processing everything. but, we are only attending to one. But the other stuff is still there, and if it's relevant it grabs us. Is that true? Well, this was studied largely using a task called the dichotic listening task. So, literally Cherry tried to kind of replicate that cocktail party context. So, he would have participants wearing headphones. Where he could independently control the message sent to the left channel and the right channel. And their task would be something that's called shadowing. So specifically, you would take one of these channels, and in this case, it's showing the channel to right for us. It's obviously it's on the left for the participants. but that channel, would be called the attended channel. And what the participant will be told is, whatever you hear in this channel, repeat it. Okay, so he's hearing president Lincoln often read by the light of the fire, president. So, he's just reading along with everything he's hearing in this ear, ignoring everything he's hearing with that, with the other ear. Okay. So the question is, what happens to this information? is it just completely blocked out? Is it just filtered out at a very low level, and in fact, some of the early studies suggested it was. There's some famous studies by an, a, a scientist named Broadbent and Broadbent played with things like the following. He would actually have. The message in this unattended ear, in this ignored ear changed languages sometimes. You'd have a bilingual reader, so they'd read a little bit in English, and then maybe they would switch to French or Spanish, or back to English And when he asked the people afterwards, did you notice anything odd happening in the ignored channel? they would typically say no. In fact the only thing that Broadbent noted that they noticed, was when the raw perceptual characteristics of the stimulus changed. So, what I mean by that is it went from a male's voice to a female's voice, so very different frequency ranges for example or very different loudnesses. You know, basic sensory levels. If they changed a lot, that would sort of attract attention, and the person would notice that. But if that didn't, if it was the same voice, same frequency range, same volume, same intensity. Then in Broadbent studies, it seemed as though you could change others characteristic of the message, and this person would have no idea. So, he suggested something he called an early filter, where things we don't attend to get filtered out very early on in their perceptual process. However, that notion didn't seem to hold, not when people did more experiments. One of the experiments they did was very much the one Cherry suggested. They would occasionally present the subject's name in the unattended channel. And sure enough, the subject did occasionally notice that, not always, sometimes they wouldn't. But if their name was read, they would, they would sometimes notice that that had happened. They would also sometimes notice if profanity had been used. you know, why profanity? Well, it's just, you know, especially in a context like an experiment, that, that's a weird thing. It's a very odd, unusual thing. And so it seemed as though, well maybe some information is getting through. Then along came Anne Triesman. And Anne did a really interesting variant of this experiment, that I think really kind of took us to another level of understanding. She had a message, that was starting in one year. In the, here it says to be shadowed year, so that's the attended year. So everything has been flipped on this figure. This participant is now attending to her right year, the one we see here. And ignoring this ear, at least she's supposed to be. But what Anne noticed is if you start a message in the ear people are attending, shadowing but then the content, the semantic content of that moves to the other channel. So I saw the girl jumping in the street. So the sentence began in the ear you were attending to, but then it moved over to the one you're supposed to be ignoring. Meanwhile there was something else in the one you're ignoring that moves to the one you're attending. So the right thing that this person should have done, if they strictly shadowed the attendant, they should have said, I saw the girl, me that bird. So that, that's what was actually in this ear. But what they, oh, I'm sorry, they should have said. I saw the girl, song was wishing. Okay, that's what was actually presented here. But what they actually said was, I saw the girl jumping in the street. Then they would often go, oh, sorry. Because they had gone to the wrong ear, they had followed the message from the attended ear to the unattended ear. And continued it on, and then noticed, oh, I'm not supposed to be shadowing this ear, and they would go back. Okay? Now, why is that important? Well, it's important because it suggests that at the point where it was it was, I saw the girl, the, the participants knew what the message had been. And they somehow were processing this unattended one enough, to know that the proper completion to the sentence. The proper semantic, you know, the meaning of the sentence was the one that went over to the unattended ear. So, they followed it and and the fact that they followed it meant that they had to know that it was the better ending to the sentence. So that means they're processing it pretty deeply. Something about meaning, to know that I saw the girl jumping in the street. That that has a consistent meaning. So it seemed as though they were processing even up to the meaning of the unattended message. Okay. Let me take it one more step. Here's an experiment by Eric Eich that I thought was very clever, very interesting. Again dichotic listening, but here's the twist remember it's an auditory presentation. So, Eich used words that could be spelt two different ways, male, ball, blew, cell, earn, loan. So, people would hear that in the attended ear, and they would shadow it. So male, mail, ball, bawl. But notice that, when you hear a word like this you could interpret it mentally as either one of these two words. And you can interpret it as either one of these two words. Now at the same time as this word, and it is really one word, mail was presented in the attended year. A word was presented in the unattended but biased toward one or the other meanings. So, letter kind of may suggests mail as in, you know, the mail that comes in the mail. Cry biases you toward bawl this ball, bawl, wind towards this blue. Jail towards this cell. So, he would present these, you would hear simultaneously mail letter, but simultaneously, not sequentially like that, and bawl and cry. You're only supposed to be attending to these ones. And then, after the task, one of the things he did is he asked people tell me which one of these things you can remember. The ones you were supposed to be ignoring. And they couldn't remember any. I don't know. I don't remember any of those. I was shadowing these ones. And he said okay, now just write down any of these ones that you remember. And what he was interested in is how they spelled the words. And the red ones here show you how they tended to spell the word. And specifically, they tended to pick the spelling that was consistent with the unattended message. So now we're getting a fuller notion of what's going on. You're attending to something, but it seems like you are perceiving other things. And those other things, are affecting the way you think about what you're paying attention to. You may forget the unattended things and that gives you the feeling that they were never really perceived. But in fact they were and they were biasing the way you think about what you're attending to. Little complex, let me try to tie this up in a good real world example for you. And I think that example is body language. And if you kind of think of you know, text versus a real conversation. You know, what's the difference? Well, both contain information, verbal information. But when you're really talking to somebody, that verbal information also has this, has all this nonverbal communication. Has facial expressions, has smiles, grimaces, has you know hand gesticulations, all of these other things happening. And all of those you would probably never remember after you've talked to someone. You probably wouldn't remember specifically what any of that non-verbal stuff was. But again, the claim is, you're listening to the words, and that all of this non-verbal will bias the way you think about the words. So, for example, do you believe this person's being honest? Now they're saying something to you but do you belie, do you think that they're being honest? Well, if you don't it's probably not because of what they're saying, but it's because of how they say it. And you may not even be aware, you may not be able to say, no, no, you know? You've been, you've been flexing these muscles while you're telling while you're telling me that, that suggests fear and deception. you know, the real clever people could do that. There was a show called Lie to Me Once, where that was the guy's thing. You and I can't do it that way. But we can still feel it. And we can still just say, yeah, you know what? I'm not buying it. I don't believe you. I'm not sure why, but I don't believe you. That seems to be how we process the world, focusing on the attended. Unattended none the less, affecting the way we think about things and then seemingly disappearing. Kind of fascinating, kind of, I think it's kind of, but I'm a psychology geek. I'm hoping you guys are becoming psychology geeks as well. here's some followup. Now, you know, it's, it's so hard to cover, psychology in, in these quick little bites. there's a lot more to perception and to attention and selection, than I'm going to be able to do. So, I wanted to push you, these two are fascinating, this, this concept called change blindness. What it will show you is that even the stuff we're paying attention to, we're not paying attention to every aspect of it. And in fact, sometimes some radical changes can happen. so in some of these experiments, a person is talking to one person, and then we pull a little trick on them and we swap the person they're talking to. And very often, they don't even notice that the person they're talking to has changed. They can be blind to change, even for things they're paying attention to. So there's a demonstration of this in a, in a laboratory kind of context. And then there's a demonstration of this in a real world kind of conte, context. And they're really fascinating. here's a little bit more about body language, to follow up on that last point. she's an expert on body language and, and, you know, gives you a good sense of how body detection, for example occurs. if you want to try a dichotic listening task, here's a website where you can kind of give, give it a go, get a feel for what it's like. And here, just some more interesting demonstrations related to perception, selection, So, all of these meant to give you a much more palpable real experience with some of these concepts we've been talking about. Alright? Next lecture consciousness, self awareness and how we can experimentally tap it. Not just in humans but in animals too. All right? I hope you're back for that one. Have a great day. Bye-bye.
