WEBVTT 00:00:00.040 --> 00:00:02.460 The following content is provided under a Creative 00:00:02.460 --> 00:00:03.870 Commons license. 00:00:03.870 --> 00:00:06.910 Your support will help MIT OpenCourseWare continue to 00:00:06.910 --> 00:00:10.560 offer high quality educational resources for free. 00:00:10.560 --> 00:00:13.460 To make a donation or view additional materials from 00:00:13.460 --> 00:00:19.290 hundreds of MIT courses, visit MIT OpenCourseWare at 00:00:19.290 --> 00:00:20.540 ocw.mit.edu. 00:00:28.020 --> 00:00:30.670 PROFESSOR: Last time, we talked about attention and the 00:00:30.670 --> 00:00:32.990 idea that attention has got some properties. 00:00:32.990 --> 00:00:35.270 We're very limited in what we can focus on. 00:00:35.270 --> 00:00:37.580 We attend to less than we might guess in our 00:00:37.580 --> 00:00:38.620 environment. 00:00:38.620 --> 00:00:40.730 On the other hand, there are channels of information that 00:00:40.730 --> 00:00:44.460 sneak into us unconsciously or with minimal attention. 00:00:44.460 --> 00:00:48.030 And experimental research has shown us what requires our 00:00:48.030 --> 00:00:51.290 focused attention to be noticed and what can sneak in 00:00:51.290 --> 00:00:55.290 through pathways, things like features in our environment. 00:00:55.290 --> 00:00:58.480 And so I want to talk to you today about two kinds of 00:00:58.480 --> 00:01:02.690 spectacular disorders of attention in a higher level 00:01:02.690 --> 00:01:05.390 vision and insight they give us into the 00:01:05.390 --> 00:01:06.600 brain basis of attention. 00:01:06.600 --> 00:01:10.720 And again, the message is how much we construct by the rules 00:01:10.720 --> 00:01:13.110 of our mind and brain the environment that 00:01:13.110 --> 00:01:14.940 we see around us. 00:01:14.940 --> 00:01:16.890 So we'll talk about blindsight. 00:01:16.890 --> 00:01:19.690 That's a great name, the paradoxical state that people 00:01:19.690 --> 00:01:23.580 are cortically blind, but they kind of perceive some things. 00:01:23.580 --> 00:01:25.430 So we'll talk about that. 00:01:25.430 --> 00:01:25.570 What is it? 00:01:25.570 --> 00:01:27.380 What do we know about its brain basis? 00:01:27.380 --> 00:01:29.430 What system of unconscious perception 00:01:29.430 --> 00:01:32.030 might be in our brains? 00:01:32.030 --> 00:01:35.300 In these patients, it's their only visual system. 00:01:35.300 --> 00:01:38.640 In you and I, it's something in us, and we don't know 00:01:38.640 --> 00:01:40.435 exactly what it's doing relative to our conscious 00:01:40.435 --> 00:01:41.420 visual system. 00:01:41.420 --> 00:01:44.100 But we have the same brain system available to us. 00:01:44.100 --> 00:01:46.780 And then neglect, what it is, its brain basis, and how it 00:01:46.780 --> 00:01:50.330 teaches us again how we construct the world around us 00:01:50.330 --> 00:01:52.960 to know what space we're in and what's around us. 00:01:55.570 --> 00:01:59.000 So a reminder, and I think you know this well by now that the 00:01:59.000 --> 00:02:01.830 world out there is divided into a left and right visual 00:02:01.830 --> 00:02:04.810 field as we look for it in the middle, that the information 00:02:04.810 --> 00:02:07.650 from the left visual field goes through your brain and 00:02:07.650 --> 00:02:10.539 ends up shown in the right primary visual cortex, from 00:02:10.539 --> 00:02:12.060 the right visual field into your left 00:02:12.060 --> 00:02:14.230 primary visual cortex. 00:02:14.230 --> 00:02:16.850 But there's one other pathway we haven't talked about very 00:02:16.850 --> 00:02:20.730 much which goes to a structure called the superior 00:02:20.730 --> 00:02:21.060 colliculus. 00:02:21.060 --> 00:02:23.450 It's part of your midbrain. 00:02:23.450 --> 00:02:26.510 And it's the system we think gives rise to the possibility 00:02:26.510 --> 00:02:28.090 of sensation without perception. 00:02:28.090 --> 00:02:30.230 That phrase, sensation without perception, is a good one to 00:02:30.230 --> 00:02:31.420 describe blindsight. 00:02:31.420 --> 00:02:33.070 And we'll describe it in a moment. 00:02:33.070 --> 00:02:37.080 So from your retina, where all vision has to go through, a 00:02:37.080 --> 00:02:38.750 little bit of information-- 00:02:38.750 --> 00:02:40.730 a small number of fibers-- go to part of your brain that 00:02:40.730 --> 00:02:43.450 controls your pupillary reflexes, what makes your 00:02:43.450 --> 00:02:47.270 pupils get wider or smaller to see. 00:02:47.270 --> 00:02:51.720 90% of the fibers coming in, the fibers come from your eye 00:02:51.720 --> 00:02:55.010 and go through the lateral geniculate or through the 00:02:55.010 --> 00:02:57.890 major system that you've heard about from Melissa that 00:02:57.890 --> 00:03:00.230 connect to your primary visual cortex. 00:03:00.230 --> 00:03:02.760 And then, there's one other small visual pathway from your 00:03:02.760 --> 00:03:05.520 retina to this superior colliculus sometimes called a 00:03:05.520 --> 00:03:06.760 tectopulvinar system. 00:03:06.760 --> 00:03:09.580 So it's a small pathway from your eyes in terms of the 00:03:09.580 --> 00:03:13.140 number of nerve fibers. 00:03:13.140 --> 00:03:15.350 And so people said, well, can we say what's not done by the 00:03:15.350 --> 00:03:20.090 major visual pathway that goes from the eye to the cortex? 00:03:20.090 --> 00:03:23.130 What's done by this other small pathway? 00:03:23.130 --> 00:03:25.090 And one of the ways they looked at it originally all 00:03:25.090 --> 00:03:28.710 the way back in 1881 was to create in dogs bilateral 00:03:28.710 --> 00:03:29.820 occipital lesions. 00:03:29.820 --> 00:03:30.900 So now, they're cortically blind. 00:03:30.900 --> 00:03:32.390 They're not retinally blind. 00:03:32.390 --> 00:03:33.220 They're cortically blind. 00:03:33.220 --> 00:03:34.540 It's in the cortex. 00:03:34.540 --> 00:03:35.670 And what could these animals do? 00:03:35.670 --> 00:03:36.540 And they were very impressed. 00:03:36.540 --> 00:03:39.140 Although these animals didn't recognize many things, they 00:03:39.140 --> 00:03:41.760 could steer their way around their environment. 00:03:41.760 --> 00:03:43.330 They wouldn't bump into things. 00:03:43.330 --> 00:03:47.360 If you had a blindfold on or if you were retinally blind 00:03:47.360 --> 00:03:49.250 and weren't given any opportunity to know your 00:03:49.250 --> 00:03:51.870 environment, you would bump into things, right? 00:03:51.870 --> 00:03:54.530 But these animals seemed to steer their way around things 00:03:54.530 --> 00:03:56.510 pretty well. 00:03:56.510 --> 00:03:59.970 And they can do some other very simple tasks even though 00:03:59.970 --> 00:04:02.190 they ought to have been seeing nothing. 00:04:02.190 --> 00:04:04.640 So this is a suggestion in animals that there's something 00:04:04.640 --> 00:04:07.910 in the brains of primates that gives you some information 00:04:07.910 --> 00:04:11.570 that doesn't go through your conscious cortex. 00:04:11.570 --> 00:04:14.640 And then, a number of patient studies in patients with 00:04:14.640 --> 00:04:17.510 naturally occurring injuries have really shown us, given us 00:04:17.510 --> 00:04:20.230 a chance to experiment on them in a human and relate them to 00:04:20.230 --> 00:04:22.000 human experience. 00:04:22.000 --> 00:04:26.550 So here's a patient who had a large injury, a large bleed, 00:04:26.550 --> 00:04:28.410 in the right visual cortex. 00:04:28.410 --> 00:04:31.070 So because of this, this patient, this man was blind in 00:04:31.070 --> 00:04:32.550 the left visual field. 00:04:32.550 --> 00:04:33.860 This field was fine. 00:04:33.860 --> 00:04:35.580 This field was blind. 00:04:35.580 --> 00:04:38.770 Cortically blind. 00:04:38.770 --> 00:04:43.770 And the way that people figure out in what way are you blind, 00:04:43.770 --> 00:04:46.590 what parts of the world do you see and do you not see, is 00:04:46.590 --> 00:04:48.610 they'll put you in front of a computer monitor. 00:04:48.610 --> 00:04:51.350 And they'll turn on lights in various locations. 00:04:51.350 --> 00:04:54.760 And they'll create a map like this, which shows you where 00:04:54.760 --> 00:04:58.370 you respond when a light comes on and where you don't see it. 00:04:58.370 --> 00:05:00.440 So your job, basically you just look in the middle. 00:05:00.440 --> 00:05:02.520 And you say, push a button when a light comes on. 00:05:02.520 --> 00:05:03.080 So you're waiting. 00:05:03.080 --> 00:05:06.530 And a light comes on somewhere on the monitor. 00:05:06.530 --> 00:05:08.610 So what this picture is showing you is that the person 00:05:08.610 --> 00:05:10.940 could respond when the lights came on anywhere on the left 00:05:10.940 --> 00:05:15.110 side, but never responded, never said a light came on on 00:05:15.110 --> 00:05:15.660 the right side. 00:05:15.660 --> 00:05:17.780 People call this perimetry. 00:05:17.780 --> 00:05:21.070 It's a standard neurological test of visual difficulty. 00:05:21.070 --> 00:05:24.400 Here's a person whose injury harms only a quadrant of their 00:05:24.400 --> 00:05:24.970 visual field. 00:05:24.970 --> 00:05:28.410 So they never respond when a light turns on in that quarter 00:05:28.410 --> 00:05:30.090 of the world out there. 00:05:30.090 --> 00:05:31.840 But the other three quarters, they respond to. 00:05:31.840 --> 00:05:33.500 So that's a way of testing what do you do. 00:05:33.500 --> 00:05:35.470 And you're not asking them anything sophisticated, just 00:05:35.470 --> 00:05:36.060 did a light come on. 00:05:36.060 --> 00:05:36.980 Is that OK? 00:05:36.980 --> 00:05:39.480 So for this patient, here's the mapping. 00:05:39.480 --> 00:05:41.650 This patient was fine in the right visual field. 00:05:41.650 --> 00:05:42.540 This is one eye. 00:05:42.540 --> 00:05:44.980 This is the other eye. 00:05:44.980 --> 00:05:46.230 And terrible-- 00:05:46.230 --> 00:05:48.990 with a few spots a little bit better-- because lesions 00:05:48.990 --> 00:05:52.120 occurring naturally in people are seldom perfect lesions. 00:05:52.120 --> 00:05:55.720 But you can see that all this area that's dark are areas 00:05:55.720 --> 00:05:58.260 that, when a light came on in the left visual field, this 00:05:58.260 --> 00:06:02.580 man never responded that anything had turned on. 00:06:02.580 --> 00:06:04.140 There's nothing simpler, right, than a light 00:06:04.140 --> 00:06:05.600 turning on and off. 00:06:05.600 --> 00:06:09.110 He did not experience anything turning on in that way in the 00:06:09.110 --> 00:06:12.170 left half of the world. 00:06:12.170 --> 00:06:18.512 So they noticed as they gave this test that even though he 00:06:18.512 --> 00:06:21.490 was saying, I don't see anything, nothing's happening, 00:06:21.490 --> 00:06:24.690 that when they flash something in that cortically blind 00:06:24.690 --> 00:06:28.290 field, he would move his eyes in that direction as if 00:06:28.290 --> 00:06:30.290 something in his mind and brain felt 00:06:30.290 --> 00:06:31.075 something had happened. 00:06:31.075 --> 00:06:34.340 Not only something happened, but roughly where it happened. 00:06:34.340 --> 00:06:36.480 But that information was not available to 00:06:36.480 --> 00:06:37.250 his conscious mind. 00:06:37.250 --> 00:06:39.280 He's never pushing a button that he says he saw it. 00:06:39.280 --> 00:06:40.380 He always says nothing. 00:06:40.380 --> 00:06:41.740 I'm waiting for something to come on. 00:06:41.740 --> 00:06:43.960 And if it comes on in his good field, he responds. 00:06:43.960 --> 00:06:45.020 Does that make sense, OK? 00:06:45.020 --> 00:06:46.860 But something seemed to do it. 00:06:46.860 --> 00:06:48.920 And when they found that it was better than chance in the 00:06:48.920 --> 00:06:51.510 left visual field, about things like if they put on a 00:06:51.510 --> 00:06:53.240 bigger patch of light. 00:06:53.240 --> 00:06:55.650 He could tell if they gave him a short line or a long line. 00:06:55.650 --> 00:06:59.300 Now, he would never say, I see the line. 00:06:59.300 --> 00:07:02.670 You would have to make him make a guess. 00:07:02.670 --> 00:07:05.100 So when you read the papers, it's something like, I don't 00:07:05.100 --> 00:07:05.550 see anything. 00:07:05.550 --> 00:07:06.210 I don't see anything. 00:07:06.210 --> 00:07:07.370 Well, you must guess. 00:07:07.370 --> 00:07:08.540 Is it a short line or a long line? 00:07:08.540 --> 00:07:09.410 I don't see it. 00:07:09.410 --> 00:07:10.660 There's no basis for me to guess. 00:07:10.660 --> 00:07:12.220 It'll be a completely random guess. 00:07:12.220 --> 00:07:13.810 But you must guess, OK? 00:07:13.810 --> 00:07:15.190 Short or long? 00:07:15.190 --> 00:07:17.980 And then, if the lines are far enough apart in size, he's 00:07:17.980 --> 00:07:18.806 almost 100%-- 00:07:18.806 --> 00:07:20.690 97% accurate. 00:07:20.690 --> 00:07:24.070 If he's forced to guess but he never has the experience that 00:07:24.070 --> 00:07:26.650 he sees the line, he's just forced to guess and told that 00:07:26.650 --> 00:07:27.700 it's two lines. 00:07:27.700 --> 00:07:31.210 Or he can judge things like, is it a circle or a cross? 00:07:31.210 --> 00:07:32.800 Is it an x or an o? 00:07:32.800 --> 00:07:35.060 But he can't do something like a square versus a rectangle. 00:07:35.060 --> 00:07:36.630 It's very limited. 00:07:36.630 --> 00:07:38.710 Subjectively, he always feels he sees nothing. 00:07:38.710 --> 00:07:42.780 If he's given two choices, for some things he can make the 00:07:42.780 --> 00:07:46.800 correct choice if he's forced to make a guess. 00:07:46.800 --> 00:07:49.170 And there's other sophisticated ways, again, to 00:07:49.170 --> 00:07:52.210 show that even though he's unconscious of anything in his 00:07:52.210 --> 00:07:56.210 blind field, something in his mind and brain is processing 00:07:56.210 --> 00:07:57.410 information there. 00:07:57.410 --> 00:07:59.710 So here, they had a thing where he pushed a button when 00:07:59.710 --> 00:08:01.010 a light came on. 00:08:01.010 --> 00:08:02.500 This is his good field. 00:08:02.500 --> 00:08:07.050 And it takes him, on average, 359 milliseconds. 00:08:07.050 --> 00:08:08.080 Now, they do the same thing. 00:08:08.080 --> 00:08:09.250 This is his good field. 00:08:09.250 --> 00:08:11.690 But they put on at the same time a light 00:08:11.690 --> 00:08:13.320 in his blind field. 00:08:13.320 --> 00:08:16.620 And when they do that, his time goes up by about a tenth 00:08:16.620 --> 00:08:20.440 of a second as if the distraction in the blind field 00:08:20.440 --> 00:08:23.130 was slightly distracting him from making that button press. 00:08:23.130 --> 00:08:26.370 So another objective way of demonstrating that some 00:08:26.370 --> 00:08:29.780 information has been processed in the blind field even though 00:08:29.780 --> 00:08:31.820 he never says he feels like something's happening there. 00:08:34.500 --> 00:08:37.419 So here's one more patient, and the last one I'll show you 00:08:37.419 --> 00:08:41.470 of this kind, who had the unfortunate occurrence of 00:08:41.470 --> 00:08:45.270 having two strokes, one in the left occipital cortex and one 00:08:45.270 --> 00:08:50.230 in the right occipital cortex, about 36 days apart. 00:08:50.230 --> 00:08:52.910 So now, he was blind in both fields by the time he had had 00:08:52.910 --> 00:08:53.820 both of his strokes. 00:08:53.820 --> 00:08:56.140 So he was a very unlucky person. 00:08:56.140 --> 00:08:59.140 Here in the dark is the missing cortex 00:08:59.140 --> 00:09:00.390 that has died away. 00:09:09.700 --> 00:09:13.580 Now, always the problems with humans is the injuries are not 00:09:13.580 --> 00:09:15.430 controlled and precise. 00:09:15.430 --> 00:09:19.550 And so here's two examples, one in monkeys, an incredibly 00:09:19.550 --> 00:09:23.110 clever experiment to get a monkey to tell you what he or 00:09:23.110 --> 00:09:25.380 she is thinking about. 00:09:25.380 --> 00:09:27.550 And then, one with infants as well, human infants. 00:09:27.550 --> 00:09:29.600 And how do you get a monkey to talk to you about their 00:09:29.600 --> 00:09:30.900 subjective experience? 00:09:30.900 --> 00:09:33.230 The striking thing about blindside is the person's 00:09:33.230 --> 00:09:34.110 saying, I see nothing. 00:09:34.110 --> 00:09:34.670 I see nothing. 00:09:34.670 --> 00:09:38.210 I see nothing, even as he walks past obstacles with 00:09:38.210 --> 00:09:40.600 precision and carefulness. 00:09:40.600 --> 00:09:43.025 So here, what it is, they took monkeys and made unilateral 00:09:43.025 --> 00:09:44.060 lesions in them. 00:09:44.060 --> 00:09:47.090 There's a control monkey and three where they surgically 00:09:47.090 --> 00:09:50.290 removed, as precisely as they could, the left occipital 00:09:50.290 --> 00:09:53.510 visual cortex and the corpus callosum that connects the 00:09:53.510 --> 00:09:55.050 left and the right. 00:09:55.050 --> 00:09:56.620 And the first task-- and I'll show you in a moment-- was to 00:09:56.620 --> 00:09:58.470 touch a light when it comes on. 00:09:58.470 --> 00:10:01.730 And the second half is the clever design to get the 00:10:01.730 --> 00:10:05.810 monkey to tell you what he or she subjectively 00:10:05.810 --> 00:10:08.550 feels is going on. 00:10:08.550 --> 00:10:11.370 So here's the video they would make of the monkey. 00:10:11.370 --> 00:10:13.790 And in one case, here's the light coming on. 00:10:13.790 --> 00:10:16.030 So the monkeys had left removal. 00:10:16.030 --> 00:10:19.140 So this is the blind side. 00:10:19.140 --> 00:10:22.310 These bars show you how often they point correctly to a 00:10:22.310 --> 00:10:23.520 light going on. 00:10:23.520 --> 00:10:27.060 And under this circumstance, forced to point, forced to 00:10:27.060 --> 00:10:29.850 point, here's the control animal. 00:10:29.850 --> 00:10:32.420 And you can see that the animals who are blind in this 00:10:32.420 --> 00:10:34.190 field do almost perfectly. 00:10:34.190 --> 00:10:37.950 When they're forced to point, they pick almost perfectly 00:10:37.950 --> 00:10:42.020 which stimulus comes on in the blind field. 00:10:42.020 --> 00:10:45.205 Now, they add one more thing to the experiment. 00:10:45.205 --> 00:10:49.380 They have a number of lights on the good side. 00:10:49.380 --> 00:10:53.370 Here is a response that they can push to signal "I saw 00:10:53.370 --> 00:10:56.540 nothing." And if they truly saw nothing, they get the 00:10:56.540 --> 00:11:00.250 juice reward for which they're working for. 00:11:00.250 --> 00:11:01.912 But there's a light that can come on here in their bad 00:11:01.912 --> 00:11:04.290 field on their right side. 00:11:04.290 --> 00:11:05.800 Now, what happens? 00:11:05.800 --> 00:11:08.570 Here's the control monkey doing perfectly well for the 00:11:08.570 --> 00:11:12.410 lights on this side, lights on this side, and when nothing is 00:11:12.410 --> 00:11:14.400 happening pushing this bar to signal 00:11:14.400 --> 00:11:15.450 that nothing is happening. 00:11:15.450 --> 00:11:16.570 Sometimes, no light comes on. 00:11:16.570 --> 00:11:19.330 So now, the monkeys will have to say, "I see nothing," by 00:11:19.330 --> 00:11:21.830 pushing this big panel up here if nothing seems 00:11:21.830 --> 00:11:23.230 to have turned on. 00:11:23.230 --> 00:11:26.660 But look what happens to the monkeys with the cortical 00:11:26.660 --> 00:11:28.230 lesions on the left. 00:11:28.230 --> 00:11:32.230 When this light comes on, they almost never say they saw it. 00:11:32.230 --> 00:11:35.070 They almost always push, "I saw nothing." 00:11:35.070 --> 00:11:39.240 When they're allowed to say "I saw nothing" by the response, 00:11:39.240 --> 00:11:41.590 then even though this thing that you know they can see-- 00:11:41.590 --> 00:11:43.330 because you see here they're responding 00:11:43.330 --> 00:11:45.630 perfectly well over here-- 00:11:45.630 --> 00:11:49.040 but when allowed to consciously respond what they 00:11:49.040 --> 00:11:52.240 see, then these black bars are all the way down. 00:11:52.240 --> 00:11:54.590 They almost never indicate they saw something. 00:11:54.590 --> 00:11:57.950 They almost always pick the response, "I saw nothing." So 00:11:57.950 --> 00:12:00.380 the monkey is telling you what his subjective experience is, 00:12:00.380 --> 00:12:02.870 which is like the humans with the cortical lesions. 00:12:02.870 --> 00:12:06.930 They're reporting they see nothing, even though some part 00:12:06.930 --> 00:12:09.750 of their brain can pick it up. 00:12:09.750 --> 00:12:10.640 How about in humans? 00:12:10.640 --> 00:12:14.550 So sometimes humans, children, infants, for medical reasons 00:12:14.550 --> 00:12:16.580 have to have hemispherectomies in the first year. 00:12:16.580 --> 00:12:20.050 These are unfortunate infants who have severe brain 00:12:20.050 --> 00:12:22.160 injuries, severe epilepsy. 00:12:22.160 --> 00:12:24.540 And it's considered better to help them by removing an 00:12:24.540 --> 00:12:27.670 entire hemisphere than to let them have the severity of the 00:12:27.670 --> 00:12:28.870 epilepsy they were having. 00:12:28.870 --> 00:12:32.820 These are rare cases in very unfortunate infants. 00:12:32.820 --> 00:12:34.950 And in these infants who got this for purely medical 00:12:34.950 --> 00:12:38.150 reasons to make their lives better, they also did an 00:12:38.150 --> 00:12:41.100 experiment to show you something not only about, I 00:12:41.100 --> 00:12:43.930 think, again, what happens in our conscious visual system, 00:12:43.930 --> 00:12:48.940 but also how that system grows in infancy and the growth of a 00:12:48.940 --> 00:12:50.780 conscious cortical visual system. 00:12:50.780 --> 00:12:53.510 So here's what they did. 00:12:53.510 --> 00:12:55.960 Infants this young-- because they're in their first year-- 00:12:55.960 --> 00:12:58.880 can't even point and you can't tell them to point. 00:12:58.880 --> 00:13:01.990 So again, you have to be clever experimentally. 00:13:01.990 --> 00:13:05.360 And what they did is they watched where their eyes moved 00:13:05.360 --> 00:13:06.600 and recorded that information. 00:13:06.600 --> 00:13:08.420 And that was the behavior. 00:13:08.420 --> 00:13:10.550 Sometimes, they would have a fixation. 00:13:10.550 --> 00:13:11.630 They've always had a fixation. 00:13:11.630 --> 00:13:12.870 You're looking in the middle. 00:13:12.870 --> 00:13:16.070 And then, something would come on out of side or this side, 00:13:16.070 --> 00:13:19.420 in the blind field or in the intact field. 00:13:22.190 --> 00:13:24.080 And they would see how often would their eyes move to a 00:13:24.080 --> 00:13:25.420 stimulus in their good field, which they 00:13:25.420 --> 00:13:26.550 expected all the time. 00:13:26.550 --> 00:13:28.560 But how often would it move to the stimulus in the blind 00:13:28.560 --> 00:13:30.280 field, the eye movement? 00:13:30.280 --> 00:13:34.180 Then, they had a competition condition where you have a dot 00:13:34.180 --> 00:13:35.010 in the middle. 00:13:35.010 --> 00:13:39.350 And that fixation dot would stay on while a box appeared 00:13:39.350 --> 00:13:40.720 here or here. 00:13:40.720 --> 00:13:41.500 So the only sense-- 00:13:41.500 --> 00:13:43.920 the only difference between these two is there's a dot in 00:13:43.920 --> 00:13:47.120 the middle that can compete for what you look at. 00:13:47.120 --> 00:13:47.420 OK? 00:13:47.420 --> 00:13:49.250 It's not a big competition. 00:13:49.250 --> 00:13:51.160 It's just a boring dot that stays on. 00:13:51.160 --> 00:13:52.950 But there's a big consequence. 00:13:52.950 --> 00:13:55.020 So here's how often they moved their eyes to the target in 00:13:55.020 --> 00:13:56.610 the non-competition condition. 00:13:56.610 --> 00:13:57.620 The dot goes on. 00:13:57.620 --> 00:13:58.400 It goes off. 00:13:58.400 --> 00:14:01.640 And the box comes on in your good field or your bad field. 00:14:01.640 --> 00:14:04.720 And all these bars are up at the top. 00:14:04.720 --> 00:14:07.795 And practically every trial, at eight weeks, 10 weeks, and 00:14:07.795 --> 00:14:11.540 12 weeks of age, the infant moves his or her eyes to the 00:14:11.540 --> 00:14:14.980 stimulus whether it's in the blind field or the good field. 00:14:14.980 --> 00:14:17.370 So something in their mind and brain is letting them identify 00:14:17.370 --> 00:14:20.150 something and moves their eyes to the good field, much like 00:14:20.150 --> 00:14:23.100 we talked about before for the adults. 00:14:23.100 --> 00:14:26.100 Now, in the competition condition, you can already see 00:14:26.100 --> 00:14:27.060 it's not quite the same. 00:14:27.060 --> 00:14:30.130 If there's a dot on and the box comes on their blind 00:14:30.130 --> 00:14:33.050 field, they don't always make it to the box. 00:14:33.050 --> 00:14:37.540 That dot is capturing their conscious cortical attention 00:14:37.540 --> 00:14:40.810 and diminishing the likelihood they notice the box coming on 00:14:40.810 --> 00:14:42.240 in the blind field. 00:14:42.240 --> 00:14:44.810 And as the weeks pass from eight to 10 to 12, just a 00:14:44.810 --> 00:14:46.270 month of development, look what happens. 00:14:46.270 --> 00:14:51.530 This bar goes from a little lower, a lot lower, near zero. 00:14:51.530 --> 00:14:54.060 That is, from eight to 12 weeks, what it looks like is 00:14:54.060 --> 00:14:58.370 happening is that as the cortical system matures and 00:14:58.370 --> 00:15:04.420 the infant's consciousness is growing in some sense, now 00:15:04.420 --> 00:15:06.920 it's no longer tending to process the information in the 00:15:06.920 --> 00:15:09.470 blind field if there's competition. 00:15:09.470 --> 00:15:15.130 Because the growth of that consciousness in the cortex is 00:15:15.130 --> 00:15:19.730 suppressing the ability of the infant to communicate with 00:15:19.730 --> 00:15:22.480 unconscious systems or be guided by unconscious systems 00:15:22.480 --> 00:15:23.730 in the brain. 00:15:23.730 --> 00:15:26.370 So the cool thing is the implication of this, is all of 00:15:26.370 --> 00:15:30.740 us have this collicular system in us. 00:15:30.740 --> 00:15:32.480 It's a visual system that's been around 00:15:32.480 --> 00:15:35.600 long through evolution. 00:15:35.600 --> 00:15:39.495 All of us have this massive conscious geniculate, the one 00:15:39.495 --> 00:15:41.270 that goes into your cortex system. 00:15:41.270 --> 00:15:43.430 And that dominates this other system. 00:15:43.430 --> 00:15:46.100 And so we only see it revealed in these 00:15:46.100 --> 00:15:48.560 patients as guiding behavior. 00:15:48.560 --> 00:15:50.970 But who knows what it really does in us? 00:15:50.970 --> 00:15:52.760 Because it's quietly sitting there. 00:15:52.760 --> 00:15:55.460 We don't have conscious access to it. 00:15:55.460 --> 00:15:57.140 And who knows how much it's guiding our behavior? 00:15:57.140 --> 00:15:59.350 And it's very hard to figure that out. 00:15:59.350 --> 00:16:02.080 But it's definitely disappearing from our 00:16:02.080 --> 00:16:06.160 conscious life within the first couple months of our 00:16:06.160 --> 00:16:08.430 development. 00:16:08.430 --> 00:16:11.240 So now, I'm going to switch to the second major disorder 00:16:11.240 --> 00:16:16.010 we'll talk about, attention and neglect, and go through 00:16:16.010 --> 00:16:19.230 anosagnosia, a spectacular version of that disorder, 00:16:19.230 --> 00:16:21.100 something about how it's behaviorally measured, its 00:16:21.100 --> 00:16:24.170 brain basis, and then a few more analyses. 00:16:24.170 --> 00:16:26.570 But in the book, there's a very nice 00:16:26.570 --> 00:16:27.730 chapter about these patients. 00:16:27.730 --> 00:16:31.620 Now, patients with blindsight are extremely rare. 00:16:31.620 --> 00:16:35.800 You have to have exactly the right kind of injury to damage 00:16:35.800 --> 00:16:38.160 a lot of your occipital cortex. 00:16:38.160 --> 00:16:42.350 And those kinds of injuries rarely occur on that scale. 00:16:42.350 --> 00:16:45.100 Attention and neglect, what I'm about to describe to you, 00:16:45.100 --> 00:16:47.740 if any of you become physicians or work in hospital 00:16:47.740 --> 00:16:52.250 settings, you are guaranteed to see this a lot. 00:16:52.250 --> 00:16:56.780 A lot-- it's very, very common for patients who've had things 00:16:56.780 --> 00:16:59.380 like stroke or brain injuries of some kind or another. 00:16:59.380 --> 00:17:02.890 And a pretty typical example is from Oliver Sacks. 00:17:02.890 --> 00:17:05.630 Most of the Sacks cases are pretty rare, prosopagnosia, 00:17:05.630 --> 00:17:06.690 pretty rare. 00:17:06.690 --> 00:17:07.310 Neglect? 00:17:07.310 --> 00:17:08.950 Incredibly common in the hospital ward, 00:17:08.950 --> 00:17:10.400 in neurology service. 00:17:10.400 --> 00:17:12.455 So here, he talks about a woman, an intelligent woman in 00:17:12.455 --> 00:17:15.119 her 60s, massive stroke affecting deep or inner back 00:17:15.119 --> 00:17:17.380 portions of her right cerebral hemisphere, good 00:17:17.380 --> 00:17:18.740 intelligence and humor. 00:17:18.740 --> 00:17:21.010 And what happens to her when they bring her her dessert or 00:17:21.010 --> 00:17:24.700 coffee on her tray in the hospital? 00:17:24.700 --> 00:17:26.630 PROFESSOR: Yeah, she complains that she's not getting enough 00:17:26.630 --> 00:17:30.320 food because she's only eating food on the 00:17:30.320 --> 00:17:32.810 right half of her plate. 00:17:32.810 --> 00:17:35.680 The left half of the plate, it's as if it 00:17:35.680 --> 00:17:37.960 weren't present for her. 00:17:37.960 --> 00:17:40.540 When they say, "But Mrs. S., it is right there on the 00:17:40.540 --> 00:17:42.530 left," she seems not to understand what they say and 00:17:42.530 --> 00:17:43.580 does not look to the left. 00:17:43.580 --> 00:17:45.640 If her head is gently turned so the dessert comes into 00:17:45.640 --> 00:17:48.140 sight in the preserved right half of her field, she says, 00:17:48.140 --> 00:17:49.030 "Oh, there it is! 00:17:49.030 --> 00:17:50.720 It wasn't there before." 00:17:50.720 --> 00:17:52.130 You understand? 00:17:52.130 --> 00:17:54.450 It's as if the left half of the plate did not exist. 00:17:54.450 --> 00:17:57.740 And if they swivel her head and now that left half of her 00:17:57.740 --> 00:18:01.790 plate is in her right field, now she goes, oh my gosh! 00:18:01.790 --> 00:18:03.400 Who snuck that on my plate? 00:18:03.400 --> 00:18:05.170 Now I can finish my meal. 00:18:05.170 --> 00:18:06.090 And it's not just that. 00:18:06.090 --> 00:18:10.350 She also only puts on makeup on half her face looking in 00:18:10.350 --> 00:18:14.180 the mirror, which can lead to comical impressions. 00:18:14.180 --> 00:18:18.330 So she ignores the left half of her world. 00:18:18.330 --> 00:18:20.660 And it's not just that it isn't there. 00:18:20.660 --> 00:18:21.990 It's as if it couldn't be there. 00:18:21.990 --> 00:18:24.180 It's as if, what are you talking about there's a left 00:18:24.180 --> 00:18:25.090 half of something? 00:18:25.090 --> 00:18:26.540 I see everything. 00:18:26.540 --> 00:18:28.250 So we'll talk a little about this and understand more 00:18:28.250 --> 00:18:29.280 of it coming up. 00:18:29.280 --> 00:18:33.480 So neglect means a failure to respond or report to something 00:18:33.480 --> 00:18:35.540 that's opposite to the lesion-- contralateral means 00:18:35.540 --> 00:18:36.910 opposite to the lesion-- 00:18:36.910 --> 00:18:38.420 that can't be accounted for by simple things. 00:18:38.420 --> 00:18:41.010 These patients don't have primary visual problems. 00:18:41.010 --> 00:18:41.980 They understand language. 00:18:41.980 --> 00:18:43.180 They're paying attention. 00:18:43.180 --> 00:18:45.930 They're the ones who deny the left half of their body. 00:18:45.930 --> 00:18:47.900 They dress on one side. 00:18:47.900 --> 00:18:50.130 They eat from one side of the plate. 00:18:50.130 --> 00:18:52.100 And they also have something that I'll show you in a 00:18:52.100 --> 00:18:55.400 moment, the example because it comes back a couple times. 00:18:55.400 --> 00:18:57.360 And it sounds fancy, but it's simple. 00:18:57.360 --> 00:19:00.060 There's extinction to double simultaneous stimulation seen 00:19:00.060 --> 00:19:01.740 in the late stages. 00:19:01.740 --> 00:19:06.190 So here's what the neurologist does-- and you'll see at least 00:19:06.190 --> 00:19:08.590 one neurologist doing this in a film clip coming up-- and 00:19:08.590 --> 00:19:10.650 they do this all the time in the hospital. 00:19:10.650 --> 00:19:11.930 They'll wiggle their fingers. 00:19:11.930 --> 00:19:13.800 They'll try to get it in the middle of the patient. 00:19:13.800 --> 00:19:15.515 This isn't carefully controlled, but it's done on 00:19:15.515 --> 00:19:16.360 the bedside. 00:19:16.360 --> 00:19:17.570 They'll wiggle one side and say, do you 00:19:17.570 --> 00:19:18.580 see anything moving? 00:19:18.580 --> 00:19:21.690 Or the other side, and sometimes they wiggle both. 00:19:21.690 --> 00:19:24.570 And the typical response in neglect is already 00:19:24.570 --> 00:19:25.600 fascinating. 00:19:25.600 --> 00:19:29.920 So past the early stages of the disorder, they'll notice 00:19:29.920 --> 00:19:31.790 the thing on the left side. 00:19:31.790 --> 00:19:34.440 From their perspective, that's their neglected side. 00:19:34.440 --> 00:19:35.700 They'll notice it on the right side. 00:19:35.700 --> 00:19:36.650 That's their good side. 00:19:36.650 --> 00:19:38.420 They're noticing this finger wiggling. 00:19:38.420 --> 00:19:39.550 They're noticing that finger wiggling. 00:19:39.550 --> 00:19:43.800 But when the physician wiggles both fingers at the same time, 00:19:43.800 --> 00:19:46.490 then the patient will only notice the 00:19:46.490 --> 00:19:47.680 one on the good side. 00:19:47.680 --> 00:19:51.170 It's as if this is extinguished because this one 00:19:51.170 --> 00:19:52.850 grabs your attention. 00:19:52.850 --> 00:19:55.540 And you know they can see it by itself. 00:19:55.540 --> 00:19:59.070 So it's only when it's both sides that it's extinguished. 00:19:59.070 --> 00:19:59.950 And we'll come back to that. 00:19:59.950 --> 00:20:00.640 It's interesting. 00:20:00.640 --> 00:20:02.260 It's not that their mind can't see. 00:20:02.260 --> 00:20:04.585 But when there's competition in the two fields-- which 00:20:04.585 --> 00:20:05.980 reminds me a little bit of blindsight -- 00:20:05.980 --> 00:20:09.120 then their mind can't see it. 00:20:09.120 --> 00:20:15.930 So a strong, a fascinating and rarer piece of this, but again 00:20:15.930 --> 00:20:18.810 not very rare, is something called anosagnosia where they 00:20:18.810 --> 00:20:23.140 not only have the neglect that I just described, but they 00:20:23.140 --> 00:20:25.700 deny any problem at all. 00:20:25.700 --> 00:20:29.200 So typically, the patient has a big, right lesions, about 5% 00:20:29.200 --> 00:20:30.720 of neglect cases. 00:20:30.720 --> 00:20:34.460 And a very fascinating neuroscientist, you may have 00:20:34.460 --> 00:20:35.170 read some of his stuff. 00:20:35.170 --> 00:20:40.330 He's a very creative mind, Ramachandran at UCSD, did some 00:20:40.330 --> 00:20:43.110 semi-experiments with some of these patients. 00:20:43.110 --> 00:20:46.590 So these are patients with right sided lesions. 00:20:46.590 --> 00:20:49.220 It says they have weakness or non-use of their left hand. 00:20:49.220 --> 00:20:50.670 And so here's his dialogue with them. 00:20:50.670 --> 00:20:51.850 Can you use your right hand? 00:20:51.850 --> 00:20:53.260 And that patient's hand is fine. 00:20:53.260 --> 00:20:54.100 Yes. 00:20:54.100 --> 00:20:56.230 Can use your left hand? 00:20:56.230 --> 00:20:56.930 Yes. 00:20:56.930 --> 00:20:59.870 The patient can't use her left hand. 00:20:59.870 --> 00:21:01.900 Are your hands equally strong? 00:21:01.900 --> 00:21:02.940 Yes. 00:21:02.940 --> 00:21:05.360 Can you point to my nose with your right hand? 00:21:05.360 --> 00:21:05.860 And she does. 00:21:05.860 --> 00:21:07.200 Her right hand is fine. 00:21:07.200 --> 00:21:10.050 Can you point to my nose with your left hand? 00:21:10.050 --> 00:21:12.480 The paralyzed left hand-- it's the left hand because it's a 00:21:12.480 --> 00:21:13.870 right hemisphere stroke-- 00:21:13.870 --> 00:21:15.850 does not move at all. 00:21:15.850 --> 00:21:17.310 Are you pointing to my nose? 00:21:17.310 --> 00:21:18.010 Yes. 00:21:18.010 --> 00:21:19.950 Can clearly see it pointing? 00:21:19.950 --> 00:21:22.670 Yes, it's about two inches from your nose. 00:21:22.670 --> 00:21:23.350 Can you clap? 00:21:23.350 --> 00:21:24.270 Of course I can clap. 00:21:24.270 --> 00:21:25.925 And here's what she does. 00:21:25.925 --> 00:21:26.960 Are you clapping? 00:21:26.960 --> 00:21:28.520 Yes, I'm clapping. 00:21:28.520 --> 00:21:29.680 She can't move her left side. 00:21:29.680 --> 00:21:33.710 But in every way in this patient's reports, she seems 00:21:33.710 --> 00:21:37.680 to deny in a deep sense that there's any problem in her 00:21:37.680 --> 00:21:40.910 performance or any weakness of any kind. 00:21:40.910 --> 00:21:45.370 So he wanted to do a couple little experiments to show 00:21:45.370 --> 00:21:51.120 that it's not just that they're saying, but they'll 00:21:51.120 --> 00:21:51.820 follow all the way through. 00:21:51.820 --> 00:21:55.540 So imagine that you had injured your left 00:21:55.540 --> 00:21:56.900 arm, was in a cast. 00:21:56.900 --> 00:21:59.930 And somebody asked you, I'm going to give you two choices. 00:21:59.930 --> 00:22:02.480 I'm going to give you $5 to screw in a light bulb-- 00:22:02.480 --> 00:22:04.340 your left arm is in a cast now-- 00:22:04.340 --> 00:22:06.400 or $10 to tie your shoe laces. 00:22:06.400 --> 00:22:09.080 Which would you take? 00:22:09.080 --> 00:22:09.740 The light bulb, right? 00:22:09.740 --> 00:22:12.360 Because it's going to be hard to tie your shoe laces with 00:22:12.360 --> 00:22:13.770 one arm out of action. 00:22:13.770 --> 00:22:14.970 This person is the same way. 00:22:14.970 --> 00:22:15.730 She's had a stroke. 00:22:15.730 --> 00:22:17.160 Her left arm's not functioning. 00:22:17.160 --> 00:22:21.060 She should definitely take the light bulb. 00:22:21.060 --> 00:22:22.480 She takes the shoe laces. 00:22:22.480 --> 00:22:24.710 When the physician, Ramachandran, describes as she 00:22:24.710 --> 00:22:28.300 sits there with one hand trying to flop the laces 00:22:28.300 --> 00:22:32.320 together making no progress at all, he says finally he has to 00:22:32.320 --> 00:22:33.550 end the exercise. 00:22:33.550 --> 00:22:34.710 He can't take it anymore. 00:22:34.710 --> 00:22:37.380 She'll just keep going until-- 00:22:37.380 --> 00:22:41.815 So she just doesn't process that her left side of her 00:22:41.815 --> 00:22:42.970 body's not working. 00:22:42.970 --> 00:22:46.130 And then, he does another experiment more impressive. 00:22:46.130 --> 00:22:49.060 I can use one of these, I think. 00:22:49.060 --> 00:22:53.870 So imagine this was a tray of cocktail glasses full of 00:22:53.870 --> 00:22:55.670 water, let's say to the very brim. 00:22:55.670 --> 00:22:58.190 Imagine there's three here and three-- six things. 00:22:58.190 --> 00:22:59.410 You can see they're right at the top. 00:22:59.410 --> 00:23:01.350 And you're just hoping that the person bringing it to you 00:23:01.350 --> 00:23:02.770 doesn't spill it on you. 00:23:02.770 --> 00:23:07.320 And the person brings it over to you, actually filled with 00:23:07.320 --> 00:23:10.110 water and asks a patient to hold the tray. 00:23:10.110 --> 00:23:12.580 OK, can I pick on you for one second? 00:23:12.580 --> 00:23:13.830 Imagine you had only-- 00:23:16.290 --> 00:23:18.250 how would you hold the tray if one arm was 00:23:18.250 --> 00:23:19.912 unavailable for you? 00:23:19.912 --> 00:23:22.270 OK, I'm bringing this over. 00:23:22.270 --> 00:23:23.810 You have to watch, very exciting. 00:23:23.810 --> 00:23:24.640 There's water. 00:23:24.640 --> 00:23:26.760 Yes, OK. 00:23:26.760 --> 00:23:28.690 How would you had if two hands were available to you? 00:23:28.690 --> 00:23:29.300 OK, thank you. 00:23:29.300 --> 00:23:29.640 OK, right? 00:23:29.640 --> 00:23:31.660 That's easy for you to imagine how you would hold it. 00:23:31.660 --> 00:23:33.390 They walk over to the patient with all this stuff. 00:23:33.390 --> 00:23:34.030 They hand it to her. 00:23:34.030 --> 00:23:35.120 And what does the patient do? 00:23:35.120 --> 00:23:36.840 She puts out her right hand on the right side. 00:23:36.840 --> 00:23:38.590 And the whole thing falls over. 00:23:38.590 --> 00:23:41.760 They're trying to demonstrate it goes all the way through. 00:23:41.760 --> 00:23:44.200 This person really believes there's not a problem. 00:23:44.200 --> 00:23:46.610 And they can be doused in water for a moment-- and I'm 00:23:46.610 --> 00:23:48.220 sure dried appropriately-- 00:23:48.220 --> 00:23:53.030 and still deny there's any problem at all. 00:23:53.030 --> 00:23:55.100 Now, one thing they can do-- and this is a weird line of 00:23:55.100 --> 00:23:58.760 research, but there's a number of papers that show this. 00:23:58.760 --> 00:24:00.580 And I'm not recommending you do this at home because 00:24:00.580 --> 00:24:04.290 actually, it's worse than it sounds. 00:24:04.290 --> 00:24:06.750 They take a syringe with cold water, and they put it into 00:24:06.750 --> 00:24:08.510 the left ear, the image is here. 00:24:08.510 --> 00:24:09.650 The patient's eye starts to move. 00:24:09.650 --> 00:24:11.020 They get a nystagmus. 00:24:11.020 --> 00:24:13.370 And they ask them how they feel. 00:24:13.370 --> 00:24:16.790 And then she says, my ear is very cold. 00:24:16.790 --> 00:24:18.040 But other than that, I'm fine. 00:24:20.530 --> 00:24:22.070 But they've given her a little bit of a 00:24:22.070 --> 00:24:24.110 shock in the left ear. 00:24:24.110 --> 00:24:27.220 And now, he does the interesting experiment. 00:24:27.220 --> 00:24:28.700 Do you feel OK? 00:24:28.700 --> 00:24:29.940 She says her ear is cold. 00:24:29.940 --> 00:24:31.180 Can you use your hands? 00:24:31.180 --> 00:24:34.020 At this moment when they've done something in the left ear 00:24:34.020 --> 00:24:37.250 that wakes up the opposite right hemisphere. 00:24:37.250 --> 00:24:39.405 I can use my right arm, but not my left arm. 00:24:39.405 --> 00:24:41.310 I want to move it, but it doesn't move. 00:24:41.310 --> 00:24:43.370 This happens just in a moment from the cold 00:24:43.370 --> 00:24:44.660 syringe in her ear. 00:24:44.660 --> 00:24:46.690 Whose arm is this? holding up the paralyzed arm. 00:24:46.690 --> 00:24:47.900 It's mine, of course. 00:24:47.900 --> 00:24:48.730 Can you use it? 00:24:48.730 --> 00:24:51.330 No, it's paralyzed-- like, what kind of doctor do I have? 00:24:51.330 --> 00:24:53.330 It's paralyzed, of course. 00:24:53.330 --> 00:24:55.360 Now, here's something really fun in a 00:24:55.360 --> 00:24:57.290 Sherlock Holmesian sense. 00:24:57.290 --> 00:24:58.705 How long has your arm been paralyzed? 00:24:58.705 --> 00:25:00.030 Did it start just now? 00:25:00.030 --> 00:25:02.620 Because what he's asking is, does she have a memory 00:25:02.620 --> 00:25:05.810 somewhere in her mind of her entire experience, or does she 00:25:05.810 --> 00:25:07.040 say it just started right now? 00:25:07.040 --> 00:25:07.910 I don't know how this happened. 00:25:07.910 --> 00:25:08.680 It's just not working. 00:25:08.680 --> 00:25:10.350 And she says, it's been paralyzed for 00:25:10.350 --> 00:25:12.250 several days now. 00:25:12.250 --> 00:25:14.500 About 90 minutes later when they redo this, she's back to 00:25:14.500 --> 00:25:15.880 just how she was. 00:25:15.880 --> 00:25:19.100 So they can temporarily alleviate this by this 00:25:19.100 --> 00:25:21.130 irrigation to the ear. 00:25:21.130 --> 00:25:25.730 So this denial of the left half of your body, this denial 00:25:25.730 --> 00:25:28.240 that you have any disorder whatsoever is a 00:25:28.240 --> 00:25:29.280 very striking thing. 00:25:29.280 --> 00:25:31.140 In most patients, it clears up. 00:25:31.140 --> 00:25:33.080 You saw pictures of it from Melissa. 00:25:33.080 --> 00:25:35.600 You saw movies of patients with object disorders. 00:25:35.600 --> 00:25:36.800 Those don't clear up. 00:25:36.800 --> 00:25:38.580 Balint's syndrome, spatial disorders-- 00:25:38.580 --> 00:25:40.820 those don't clear up. 00:25:40.820 --> 00:25:43.280 Anosagnosia patients grow out of it. 00:25:43.280 --> 00:25:47.750 Somehow, their brains recover over time. 00:25:47.750 --> 00:25:50.500 But again, it shows you how much attention is 00:25:50.500 --> 00:25:51.370 constructed, right? 00:25:51.370 --> 00:25:53.210 Because they have the stuff to represent 00:25:53.210 --> 00:25:54.690 their arm, their disease. 00:25:54.690 --> 00:25:56.870 That's all in their mind and brain. 00:25:56.870 --> 00:25:58.940 But the state they're in because of the brain injury 00:25:58.940 --> 00:26:01.790 lets them not construct that reality. 00:26:01.790 --> 00:26:03.390 So now, I'm going to show you measures of neglect. 00:26:03.390 --> 00:26:05.100 This is in your list just for your notes, but sort of fun 00:26:05.100 --> 00:26:06.330 just to look at the examples. 00:26:06.330 --> 00:26:07.940 So here's a patient. 00:26:07.940 --> 00:26:09.910 With these patients, they typically have right sided 00:26:09.910 --> 00:26:12.430 lesions, so the neglect is to the left half of the world. 00:26:12.430 --> 00:26:15.610 And here's a patient going to the bathroom as if all you can 00:26:15.610 --> 00:26:19.600 do is make right turns instead of going this way, as if the 00:26:19.600 --> 00:26:22.430 world weren't there, to proceed on the left. 00:26:22.430 --> 00:26:24.240 Here's another test that happens 00:26:24.240 --> 00:26:26.020 every day in a hospital. 00:26:26.020 --> 00:26:28.270 The physician has drawn these lines and says, 00:26:28.270 --> 00:26:29.700 cross out the lines. 00:26:29.700 --> 00:26:30.680 It's not perfect. 00:26:30.680 --> 00:26:31.510 The patient does that one. 00:26:31.510 --> 00:26:33.500 But look, they cross out all these lines. 00:26:33.500 --> 00:26:36.530 And the left half ones are mostly left uncrossed. 00:26:36.530 --> 00:26:39.380 It's as if they weren't there. 00:26:39.380 --> 00:26:41.060 Here's what's called a cancellation test. 00:26:41.060 --> 00:26:42.010 There's lots of letters here. 00:26:42.010 --> 00:26:44.640 And their job is to cross out all the A's. 00:26:44.640 --> 00:26:46.200 Now, let me start with neglect. 00:26:46.200 --> 00:26:47.980 You see over here, this whole area? 00:26:47.980 --> 00:26:50.430 Nothing is circled or crossed out. 00:26:50.430 --> 00:26:52.760 And you could say, well, what would happen if instead of 00:26:52.760 --> 00:26:56.970 neglect, you were like one of those blindsight patients who 00:26:56.970 --> 00:26:59.740 had a big lesion in the cortex and you were 00:26:59.740 --> 00:27:01.460 blind on one side? 00:27:01.460 --> 00:27:02.750 What would you do there? 00:27:02.750 --> 00:27:04.660 Well, it's easy for those patients because what they do 00:27:04.660 --> 00:27:06.480 is they don't see part of the world. 00:27:06.480 --> 00:27:07.860 But what do they do? 00:27:07.860 --> 00:27:11.180 They turn their head, just like you would do. 00:27:11.180 --> 00:27:12.190 They turn their head. 00:27:12.190 --> 00:27:14.370 They don't see it, but they know they don't see it. 00:27:14.370 --> 00:27:15.870 And they turn their head. 00:27:15.870 --> 00:27:18.790 And a patient who's blind on one side, loss in the visual 00:27:18.790 --> 00:27:22.200 field, gets all the lines because all you have to do if 00:27:22.200 --> 00:27:26.050 you're blind on one side is turn your head. 00:27:26.050 --> 00:27:29.100 It's not that hard in a practical sense. 00:27:29.100 --> 00:27:32.110 But if you don't imagine the left half of the world exists, 00:27:32.110 --> 00:27:33.540 where would you turn your head to? 00:27:33.540 --> 00:27:35.620 And that's what these neglect patients do, don't imagine the 00:27:35.620 --> 00:27:37.640 left half of the world exists. 00:27:37.640 --> 00:27:40.270 So here's an example of a patient reading a text. 00:27:40.270 --> 00:27:41.690 They're handed this text. 00:27:41.690 --> 00:27:45.710 The slash lines here are where this patient seems to think 00:27:45.710 --> 00:27:48.790 the left side of the page stops. 00:27:48.790 --> 00:27:52.360 OK So they're overcoming everything they know about how 00:27:52.360 --> 00:27:54.600 a sentence should be and reading this passage. 00:27:54.600 --> 00:27:58.410 The patient says, "had to pass the windows whom good morning 00:27:58.410 --> 00:28:02.560 message for the ground his with all his and he bottle." 00:28:02.560 --> 00:28:03.940 Thank you very much. 00:28:03.940 --> 00:28:07.985 It's right in front of them, but the left half of the page 00:28:07.985 --> 00:28:12.110 is just not present for this person's mind. 00:28:12.110 --> 00:28:14.550 Here is a person copying a flower. 00:28:14.550 --> 00:28:17.170 A psychologist or a neurologist draws this flower 00:28:17.170 --> 00:28:19.890 or has a flower ready to go, a drawing, and says copy 00:28:19.890 --> 00:28:21.230 everything you see. 00:28:21.230 --> 00:28:23.790 And it's not always totally perfect exactly how it works. 00:28:23.790 --> 00:28:26.240 But you can see there's a lot of the left side of this 00:28:26.240 --> 00:28:27.810 flower missing-- 00:28:27.810 --> 00:28:30.390 right in front of them. 00:28:30.390 --> 00:28:31.690 Here's a very simple one, too. 00:28:31.690 --> 00:28:33.680 Copy everything you see here. 00:28:33.680 --> 00:28:35.930 And what they see is these three things up here. 00:28:35.930 --> 00:28:38.010 Their job's to copy everything down here. 00:28:38.010 --> 00:28:39.810 They have all the time they want. 00:28:39.810 --> 00:28:40.870 Left side is neglected. 00:28:40.870 --> 00:28:42.170 And all they copy is the triangle. 00:28:42.170 --> 00:28:43.470 That's all they draw. 00:28:43.470 --> 00:28:45.850 And the tester will always say, are you done? 00:28:45.850 --> 00:28:46.800 Are you sure you're done? 00:28:46.800 --> 00:28:47.730 The person says, I'm sure I'm done. 00:28:47.730 --> 00:28:50.580 Thank you very much. 00:28:50.580 --> 00:28:52.180 Sometimes, they do something remarkable. 00:28:52.180 --> 00:28:54.410 They're shown a scene like this. 00:28:54.410 --> 00:28:56.400 Here's four trees with a house in the middle. 00:28:56.400 --> 00:28:59.740 And you can see this patient starts over here. 00:28:59.740 --> 00:29:02.120 They say, oh, there's a tree over, draws this. 00:29:02.120 --> 00:29:03.280 There's a house over here. 00:29:03.280 --> 00:29:05.990 And they jump from location to location. 00:29:05.990 --> 00:29:08.230 Every time their attention lands, they draw the right 00:29:08.230 --> 00:29:10.060 half of it. 00:29:10.060 --> 00:29:11.910 It's always as if the left were missing. 00:29:11.910 --> 00:29:16.290 And again, this idea of how constructed this is. 00:29:16.290 --> 00:29:17.250 Here's two more examples. 00:29:17.250 --> 00:29:19.430 And the clock thing, we'll talk a fair bit about. 00:29:19.430 --> 00:29:20.670 Here's a patient writing to dictation. 00:29:20.670 --> 00:29:21.890 The first sentence, they sort of stay-- 00:29:21.890 --> 00:29:23.450 but now, it's as if they were running out 00:29:23.450 --> 00:29:25.110 of room on the page. 00:29:25.110 --> 00:29:26.580 It's like they're reading, but it's writing. 00:29:26.580 --> 00:29:28.680 The left half of the page doesn't exist. 00:29:28.680 --> 00:29:30.530 Clocks are used a lot in this land, because it's kind of 00:29:30.530 --> 00:29:31.010 impressive. 00:29:31.010 --> 00:29:32.470 And we'll come back in a couple different versions 00:29:32.470 --> 00:29:32.850 about this. 00:29:32.850 --> 00:29:33.970 But look at that. 00:29:33.970 --> 00:29:37.620 They were asked to draw the time on a clock. 00:29:37.620 --> 00:29:39.950 And it's as if they could draw the time on the right side, 00:29:39.950 --> 00:29:40.910 their good side. 00:29:40.910 --> 00:29:44.620 But it's as if the left half of the clock didn't exist. 00:29:44.620 --> 00:29:48.180 Here's another patient asked to draw the time. 00:29:48.180 --> 00:29:53.720 And you see almost what seems like a struggle in the 00:29:53.720 --> 00:29:54.320 patient, right? 00:29:54.320 --> 00:29:56.010 They start on the right side. 00:29:56.010 --> 00:29:57.640 And then here, they're running out of space. 00:29:57.640 --> 00:29:59.030 They've got to cram in that 10. 00:29:59.030 --> 00:30:01.190 Their mind knows it goes to 12, right? 00:30:01.190 --> 00:30:03.580 But there's no space to put it in. 00:30:03.580 --> 00:30:07.310 And so you put them, in a sense, in a sense of conflict. 00:30:07.310 --> 00:30:08.640 And that's the top version. 00:30:08.640 --> 00:30:11.680 The bottom, they were given numbers one at a time. 00:30:11.680 --> 00:30:14.370 They were given, it tells you here, 12 and 6. 00:30:14.370 --> 00:30:16.000 So they put those in the right spots. 00:30:16.000 --> 00:30:16.990 Here comes 11. 00:30:16.990 --> 00:30:20.360 Already, 11 is like, uh-oh, right? 00:30:20.360 --> 00:30:23.790 And then, they get 4, 9. 00:30:23.790 --> 00:30:25.210 9 is not going to make it. 00:30:25.210 --> 00:30:27.530 And 10, they know it has to come after-- you can see that 00:30:27.530 --> 00:30:30.990 they put them actually in a struggle between what they 00:30:30.990 --> 00:30:33.520 know, something about where the numbers ought to go, but 00:30:33.520 --> 00:30:37.130 the impossibility of the left half existing. 00:30:37.130 --> 00:30:38.630 Now, here's something-- and we'll come back to this in a 00:30:38.630 --> 00:30:39.960 few minutes-- 00:30:39.960 --> 00:30:42.770 what happens if you just give them a piece of paper and say, 00:30:42.770 --> 00:30:43.770 write down 1 o'clock. 00:30:43.770 --> 00:30:45.160 And then, you take that piece of paper away. 00:30:45.160 --> 00:30:45.910 Write down 2 o'clock. 00:30:45.910 --> 00:30:47.190 Take that piece of paper away. 00:30:47.190 --> 00:30:47.550 Then look-- 00:30:47.550 --> 00:30:51.210 6, 7, 8, 9, 10, those are not bad, right? 00:30:51.210 --> 00:30:54.770 If they just do one of them, the very same patient who had 00:30:54.770 --> 00:30:57.690 to crowd everything on the right is quite comfortable in 00:30:57.690 --> 00:31:00.160 putting down a pretty good 9, 10, and 11 if 00:31:00.160 --> 00:31:01.830 it's just one of them. 00:31:01.830 --> 00:31:05.040 We'll come back in a little bit to experiments that help 00:31:05.040 --> 00:31:07.990 understand what's going on this case because we don't 00:31:07.990 --> 00:31:11.010 only want a scientist to say, wow, this is 00:31:11.010 --> 00:31:12.460 unbelievable and amazing. 00:31:12.460 --> 00:31:14.810 We like to say something more about how the mind is doing 00:31:14.810 --> 00:31:17.600 this and what part of their brain is important. 00:31:17.600 --> 00:31:20.110 And kind of impressively, here's a patient with eyes 00:31:20.110 --> 00:31:22.080 open mostly crowding on the right. 00:31:22.080 --> 00:31:25.640 Got the 10 on the left, but doing a better job when their 00:31:25.640 --> 00:31:27.310 eyes are closed. 00:31:27.310 --> 00:31:28.610 They missed the dial altogether. 00:31:28.610 --> 00:31:29.880 Their eyes are closed. 00:31:29.880 --> 00:31:31.120 But they actually do it-- the same patient 00:31:31.120 --> 00:31:32.250 does a better job. 00:31:32.250 --> 00:31:35.300 OK, so how does that work? 00:31:35.300 --> 00:31:38.230 And one more thing to mention is that neglect occurs across 00:31:38.230 --> 00:31:38.790 modalities. 00:31:38.790 --> 00:31:40.840 That is, when these patients have neglect, I 00:31:40.840 --> 00:31:42.390 focused on the visual. 00:31:42.390 --> 00:31:45.710 But these patients also don't do very well if they're doing 00:31:45.710 --> 00:31:47.100 things like reaching for things. 00:31:47.100 --> 00:31:48.210 It's not just vision. 00:31:48.210 --> 00:31:51.690 It's pretty much everything in the left half of the world. 00:31:51.690 --> 00:31:54.400 And you can do these kinds of things which, again, show not 00:31:54.400 --> 00:31:57.090 only their neglect but the constructed psychological 00:31:57.090 --> 00:31:58.460 nature of the neglect. 00:31:58.460 --> 00:32:00.710 It varies in ways that are interesting. 00:32:00.710 --> 00:32:02.690 So they're given a line like this and say 00:32:02.690 --> 00:32:03.860 mark the exact middle. 00:32:03.860 --> 00:32:05.210 You would draw something here. 00:32:05.210 --> 00:32:07.240 They draw here because they're going to neglect 00:32:07.240 --> 00:32:08.660 that part of the line. 00:32:08.660 --> 00:32:12.300 Then, they say read the A. So they draw the person's 00:32:12.300 --> 00:32:14.796 attention to A. And now draw it, and they get better. 00:32:14.796 --> 00:32:17.370 Then, they're asked to mark the middle. 00:32:17.370 --> 00:32:18.420 Not too good. 00:32:18.420 --> 00:32:20.030 Mark the middle-- but you see the difference here. 00:32:20.030 --> 00:32:22.120 The A is present or the B is present. 00:32:22.120 --> 00:32:24.210 And if the B is present, it pulls them over here. 00:32:24.210 --> 00:32:26.510 If the A is present, it pulls their attention over here. 00:32:26.510 --> 00:32:28.770 They put their hand at the middle and say. 00:32:28.770 --> 00:32:29.940 Now, please mark the middle. 00:32:29.940 --> 00:32:31.600 Their hand goes over here for the middle. 00:32:31.600 --> 00:32:33.635 But if they start them all the way over here, their hand will 00:32:33.635 --> 00:32:35.300 only go this far. 00:32:35.300 --> 00:32:37.360 So as you see, all these different movements are 00:32:37.360 --> 00:32:40.340 telling you that the mind is interpreting what the 00:32:40.340 --> 00:32:41.570 world is out there. 00:32:41.570 --> 00:32:44.650 If you pull a little bit the person to the left, they'll 00:32:44.650 --> 00:32:48.930 notice a little bit more of the left. 00:32:48.930 --> 00:32:50.180 Where is the injury? 00:32:52.650 --> 00:32:56.220 So almost everywhere you read still in neurology books to 00:32:56.220 --> 00:32:58.980 this day that it's in the parietal cortex. 00:32:58.980 --> 00:33:01.630 But in the last few years, people have mostly come to 00:33:01.630 --> 00:33:04.760 this idea that the damage tends to be in 00:33:04.760 --> 00:33:06.450 the temporal lobe. 00:33:06.450 --> 00:33:08.720 And what happens when the temporal lobe is injured, it 00:33:08.720 --> 00:33:11.910 knocks of the balance of attention in the left and 00:33:11.910 --> 00:33:13.680 right parietal cortex. 00:33:13.680 --> 00:33:16.610 And there's something about the activity in the right 00:33:16.610 --> 00:33:18.250 parietal cortex goes way down. 00:33:18.250 --> 00:33:20.620 That's paying attention to the left half of the world. 00:33:20.620 --> 00:33:22.990 And as patients recover from this, the balance comes back. 00:33:22.990 --> 00:33:25.260 And that's actually been measured now by brain imaging. 00:33:25.260 --> 00:33:27.700 Their attention comes back clinically, and it does in 00:33:27.700 --> 00:33:29.260 most patients. 00:33:29.260 --> 00:33:31.980 Then, the balance between the two parietal cortices get 00:33:31.980 --> 00:33:32.680 reestablished. 00:33:32.680 --> 00:33:35.690 So even though people thought the site of damage was here, 00:33:35.690 --> 00:33:38.830 the interpretation's usually here in the temporal lobe. 00:33:38.830 --> 00:33:43.160 But the consequence of that is reduced activity in this part 00:33:43.160 --> 00:33:45.010 of the brain, even if it's not physically injured. 00:33:53.640 --> 00:33:55.240 The fantastic thing is-- 00:33:55.240 --> 00:33:57.200 think about this for a second-- in order to ignore 00:33:57.200 --> 00:34:01.030 the left half of the flower, the left half of a design, the 00:34:01.030 --> 00:34:04.230 left half of a page, the left half of a clock, what do you 00:34:04.230 --> 00:34:06.680 have to know? 00:34:06.680 --> 00:34:07.910 Where the left and right are. 00:34:07.910 --> 00:34:09.440 It's not as if his eyes were closed. 00:34:09.440 --> 00:34:11.120 If your eyes were closed, you wouldn't know where left and 00:34:11.120 --> 00:34:12.810 right are on a page, right? 00:34:12.810 --> 00:34:15.980 He has to represent in his mind what is left and right 00:34:15.980 --> 00:34:17.639 reasonably accurately. 00:34:17.639 --> 00:34:20.739 And then, he extinguishes awareness that anything in the 00:34:20.739 --> 00:34:21.940 left could exist. 00:34:21.940 --> 00:34:24.120 But part of his mind has to know what is left for that to 00:34:24.120 --> 00:34:24.780 work, right? 00:34:24.780 --> 00:34:27.219 Otherwise, the digits would be all over the piece of paper, 00:34:27.219 --> 00:34:28.555 not even on the paper. 00:34:28.555 --> 00:34:30.139 He centers on the paper. 00:34:30.139 --> 00:34:32.179 He centers on the circle. 00:34:32.179 --> 00:34:33.790 Centering means I know what's left. 00:34:33.790 --> 00:34:35.070 I know what's the center. 00:34:35.070 --> 00:34:37.610 And then boom, the left disappears as a place that 00:34:37.610 --> 00:34:39.060 could exist. 00:34:39.060 --> 00:34:42.179 So these are all tasks in front of you. 00:34:42.179 --> 00:34:45.449 There's been some incredibly Sherlock Holmes like clever 00:34:45.449 --> 00:34:50.900 experiments asking whether you also neglect your imagination. 00:34:50.900 --> 00:34:52.940 Not what's in front of you, but your imagination. 00:34:52.940 --> 00:34:54.469 So here's the way they did it. 00:34:54.469 --> 00:34:57.640 Have any of you been in Milan? 00:34:57.640 --> 00:35:00.310 There's a central cathedral in part of town. 00:35:00.310 --> 00:35:02.560 It's a big deal. 00:35:02.560 --> 00:35:04.090 So they took Milanese patients, people who lived in 00:35:04.090 --> 00:35:06.110 Milan their whole lives who had strokes in the right 00:35:06.110 --> 00:35:08.920 hemisphere who had neglect, and they asked them to imagine 00:35:08.920 --> 00:35:12.130 the Piazza del Duomo, the major church there, looking at 00:35:12.130 --> 00:35:15.980 it from one side of the square or from entering from the 00:35:15.980 --> 00:35:19.160 opposite side of the square. 00:35:19.160 --> 00:35:20.370 And I'll show you the other experiment. 00:35:20.370 --> 00:35:21.340 Here's the idea. 00:35:21.340 --> 00:35:24.050 They said imagine that you're entering the square this 00:35:24.050 --> 00:35:27.730 direction so that the church is behind you, or this 00:35:27.730 --> 00:35:29.490 direction so that the church is in front of you. 00:35:29.490 --> 00:35:31.560 So you're entering the square from one side or from the 00:35:31.560 --> 00:35:32.090 other side. 00:35:32.090 --> 00:35:34.700 Now, the square that you've been too many times, that you 00:35:34.700 --> 00:35:37.260 know very well, tell me everything that's in the 00:35:37.260 --> 00:35:40.640 square as you imagine entering from one side. 00:35:40.640 --> 00:35:42.040 And here's what the patient reports. 00:35:42.040 --> 00:35:45.150 They're imagining coming out facing the church. 00:35:45.150 --> 00:35:50.650 And they report these kinds of things from this side. 00:35:50.650 --> 00:35:52.990 If that's only on the right side, they're 00:35:52.990 --> 00:35:53.740 ignoring the thing. 00:35:53.740 --> 00:35:54.890 So they say there's a cafe. 00:35:54.890 --> 00:35:57.920 There's a bookstore or whatever else there is here. 00:35:57.920 --> 00:35:59.540 That's everything that's in the square. 00:35:59.540 --> 00:36:01.450 Everything that's in the square is shown in red? 00:36:01.450 --> 00:36:03.200 Everything that's in the square. 00:36:03.200 --> 00:36:04.540 They wait just moments. 00:36:04.540 --> 00:36:06.950 And they say, now imagine instead you were coming out 00:36:06.950 --> 00:36:09.520 from the church, opposite view of the square. 00:36:09.520 --> 00:36:11.950 Tell me everything that's in the square. 00:36:11.950 --> 00:36:13.240 And here's what they tell you. 00:36:13.240 --> 00:36:15.250 The items that are in blue-- and they don't tell you the 00:36:15.250 --> 00:36:17.580 items they just told you, the locations they've just told 00:36:17.580 --> 00:36:19.900 you circled in red. 00:36:19.900 --> 00:36:22.680 So they're sitting their imagining their square. 00:36:22.680 --> 00:36:26.190 And then, they will ignore everything on the left, 00:36:26.190 --> 00:36:28.050 whatever's their subject of left. 00:36:28.050 --> 00:36:30.140 And you know they know it because all they have to do is 00:36:30.140 --> 00:36:32.000 imagine they're on the opposite side of the square, 00:36:32.000 --> 00:36:33.370 and then they report. 00:36:33.370 --> 00:36:34.090 Does that make sense? 00:36:34.090 --> 00:36:38.450 They're ignoring the left half of what they imagine the 00:36:38.450 --> 00:36:41.860 square looks like when they've been to it many times. 00:36:41.860 --> 00:36:44.400 And here's another patient doing exactly the same thing. 00:36:44.400 --> 00:36:45.770 Imagine you're coming out of the church. 00:36:45.770 --> 00:36:46.700 What's in the square? 00:36:46.700 --> 00:36:48.760 Well, here's some specific places I know. 00:36:48.760 --> 00:36:49.240 That's it? 00:36:49.240 --> 00:36:50.450 That's it. 00:36:50.450 --> 00:36:51.620 Wait a minute. 00:36:51.620 --> 00:36:55.550 Imagine you come this way into the square facing the church. 00:36:55.550 --> 00:36:57.350 What's everything in the square? 00:36:57.350 --> 00:37:01.020 And they only report the things on this side. 00:37:01.020 --> 00:37:01.870 So they're ignoring-- yeah? 00:37:01.870 --> 00:37:07.230 AUDIENCE: Does the patient realize after a few seconds? 00:37:07.230 --> 00:37:08.260 PROFESSOR: No, they never do. 00:37:08.260 --> 00:37:09.510 It's an excellent question. 00:37:09.510 --> 00:37:12.530 They just answered a moment ago one side, right? 00:37:12.530 --> 00:37:15.230 Why don't they tell you, I just told you the stuff on the 00:37:15.230 --> 00:37:17.010 other side? 00:37:17.010 --> 00:37:20.100 Because it's as if it couldn't exist. 00:37:20.100 --> 00:37:21.930 It's a little bit analogous to the patient 00:37:21.930 --> 00:37:23.390 whose arm isn't moving. 00:37:23.390 --> 00:37:25.010 And you go, do you have any problem? 00:37:25.010 --> 00:37:26.690 And they go, no, I don't have any problem. 00:37:26.690 --> 00:37:29.020 It's as if there couldn't be a problem. 00:37:29.020 --> 00:37:30.630 What are you talking about, right? 00:37:30.630 --> 00:37:33.000 So it overcomes all their knowledge and all their 00:37:33.000 --> 00:37:35.120 intelligence. 00:37:35.120 --> 00:37:38.140 It's as if I forced you to guess in detail what's in the 00:37:38.140 --> 00:37:40.200 back of the room if something new was there. 00:37:40.200 --> 00:37:41.310 And you go, there's no way. 00:37:41.310 --> 00:37:41.860 I can't see. 00:37:41.860 --> 00:37:45.180 I have no eyes in the back of my head. 00:37:45.180 --> 00:37:46.030 It's sort of like that. 00:37:46.030 --> 00:37:48.120 It's as if the left half couldn't exist. 00:37:48.120 --> 00:37:50.590 The contradiction they could note-- 00:37:50.590 --> 00:37:52.430 just a moment ago I told you the other one-- they don't 00:37:52.430 --> 00:37:56.000 notice it because something about this neglect swallows up 00:37:56.000 --> 00:37:58.350 all of your judgment. 00:37:58.350 --> 00:38:01.110 It's beautifully phrased by some neurologist as, it's as 00:38:01.110 --> 00:38:03.840 if the left half could not exist. 00:38:03.840 --> 00:38:06.990 Whenever you're thinking left, it doesn't exist. 00:38:06.990 --> 00:38:10.650 And ironically, you have to think left for that to work. 00:38:10.650 --> 00:38:11.510 That's the amazing thing. 00:38:11.510 --> 00:38:13.410 You have to go, I'm in the middle. 00:38:13.410 --> 00:38:13.970 There's a left. 00:38:13.970 --> 00:38:14.520 There's a right. 00:38:14.520 --> 00:38:15.630 Now, the left doesn't exist. 00:38:15.630 --> 00:38:17.000 And it couldn't exist. 00:38:17.000 --> 00:38:21.320 And every hint I get that it does exist, like there's food 00:38:21.320 --> 00:38:24.995 on that side or the pages usually go all the way here 00:38:24.995 --> 00:38:28.110 and makes the sentences make sense, it all disappears on 00:38:28.110 --> 00:38:30.200 you because it couldn't possibly exist. 00:38:30.200 --> 00:38:32.700 And the neat thing about that is it's striking 00:38:32.700 --> 00:38:33.380 neurologically. 00:38:33.380 --> 00:38:35.810 But that means in our own heads as we go around, we're 00:38:35.810 --> 00:38:39.330 constructing the world this way, building up two separate 00:38:39.330 --> 00:38:42.230 sides of our brain that are gluing together a picture of 00:38:42.230 --> 00:38:43.560 the world around us. 00:38:43.560 --> 00:38:45.620 And these patients lose that glue on one 00:38:45.620 --> 00:38:46.370 side of their brain. 00:38:46.370 --> 00:38:48.410 Is that OK? 00:38:48.410 --> 00:38:49.160 Here's another version. 00:38:49.160 --> 00:38:51.800 It's less flashy, but it's the same idea. 00:38:51.800 --> 00:38:54.120 Now, neglect can't get small enough. 00:38:54.120 --> 00:38:56.650 If you make something very tiny, then you 00:38:56.650 --> 00:38:57.810 don't ignore the left. 00:38:57.810 --> 00:38:59.700 Once it gets tiny enough, you can't do it. 00:38:59.700 --> 00:39:00.690 So they took advantage of that. 00:39:00.690 --> 00:39:02.680 And they show cloud like stimulus of these. 00:39:02.680 --> 00:39:04.350 But they didn't show them like this. 00:39:04.350 --> 00:39:05.880 They only had a slit. 00:39:05.880 --> 00:39:10.090 So you only saw the cloud a bit at a time. 00:39:10.090 --> 00:39:12.650 And you see one cloud, and then you see another cloud. 00:39:12.650 --> 00:39:14.870 Perhaps you'd see this cloud go by, and you see 00:39:14.870 --> 00:39:15.720 this cloud go by. 00:39:15.720 --> 00:39:18.580 And your job was to say were they identical clouds or not? 00:39:18.580 --> 00:39:20.550 And if they were not identical, on which side do 00:39:20.550 --> 00:39:22.210 they differ? 00:39:22.210 --> 00:39:26.340 So because of all your visual experiences through the slit-- 00:39:26.340 --> 00:39:29.850 which is too small for neglect to happen-- 00:39:29.850 --> 00:39:32.380 what you do is you create in your mind's eye what does that 00:39:32.380 --> 00:39:35.720 whole cloud look like as it passed through the slit in 00:39:35.720 --> 00:39:36.990 your mind's eye? 00:39:36.990 --> 00:39:38.210 And then, you see another one. 00:39:38.210 --> 00:39:39.690 And you put that up in your mind's eye. 00:39:39.690 --> 00:39:41.410 And you compare these two things that are in your 00:39:41.410 --> 00:39:43.510 imagination in your mind's eyes. 00:39:43.510 --> 00:39:46.280 And what happens is if these two things differ on the left 00:39:46.280 --> 00:39:51.830 side, the patients rarely can make that distinction. 00:39:51.830 --> 00:39:53.260 It's not because they can't see it. 00:39:53.260 --> 00:39:55.110 It's always in that narrow slit. 00:39:55.110 --> 00:39:57.620 But once they put the pieces together, they put it up in 00:39:57.620 --> 00:40:00.580 their mind, the left half disappears on them in their 00:40:00.580 --> 00:40:03.420 mind's eyes. 00:40:03.420 --> 00:40:09.060 So here's an experimental approach to think about what 00:40:09.060 --> 00:40:11.660 might be going wrong in these patients. 00:40:11.660 --> 00:40:15.250 So they used a very simple task, which is when a light 00:40:15.250 --> 00:40:16.520 comes on, you push a button. 00:40:16.520 --> 00:40:17.740 That's all the task is. 00:40:17.740 --> 00:40:20.030 Any light comes on, you push a button. 00:40:20.030 --> 00:40:21.440 And sometimes, they'll put an arrow. 00:40:21.440 --> 00:40:23.700 And sometimes, you have no information. 00:40:23.700 --> 00:40:25.740 The light comes on on the left or the right. 00:40:25.740 --> 00:40:27.910 And sometimes, they'll put on an arrow in the middle that 00:40:27.910 --> 00:40:31.445 will warn you whether the light is likely to come on in 00:40:31.445 --> 00:40:33.230 the left or the right. 00:40:33.230 --> 00:40:34.800 So sometimes, you have neutral things. 00:40:34.800 --> 00:40:35.970 You get a cross in the middle. 00:40:35.970 --> 00:40:37.220 Then, a light comes on. 00:40:37.220 --> 00:40:38.030 You don't have to say left and right. 00:40:38.030 --> 00:40:39.820 You just push a button when one of those goes on. 00:40:39.820 --> 00:40:42.250 Sometimes, he gets an error that's called valid that, 80% 00:40:42.250 --> 00:40:45.002 of the time if it's pointing this way, it will turn out on 00:40:45.002 --> 00:40:47.150 that side, 80% it will turn on this side. 00:40:47.150 --> 00:40:48.970 So 80% of the time, it's honest. 00:40:48.970 --> 00:40:51.170 And 20% of the time, it's dishonest. 00:40:51.170 --> 00:40:53.610 So here's what it looks like. 00:40:53.610 --> 00:40:56.840 You're looking here at a computer display. 00:40:56.840 --> 00:40:59.010 That thing disappears. 00:40:59.010 --> 00:41:01.060 And then, either an x is here or here. 00:41:01.060 --> 00:41:01.730 And you push a button. 00:41:01.730 --> 00:41:02.320 That's all. 00:41:02.320 --> 00:41:03.910 Or a light comes on, and you just push a button. 00:41:03.910 --> 00:41:04.410 That's all. 00:41:04.410 --> 00:41:07.420 If it came on on the left or the right, I push button. 00:41:07.420 --> 00:41:10.600 When an arrow appears, 80% of the time it's warning you 00:41:10.600 --> 00:41:13.130 where that light will appear. 00:41:13.130 --> 00:41:18.600 20%, it's dishonest and it appears on the opposite side. 00:41:18.600 --> 00:41:21.620 So you will know, how good an experimental psychologist you 00:41:21.620 --> 00:41:24.610 are right now, if I ask you which condition do you think 00:41:24.610 --> 00:41:28.110 you're the fastest to push the button, when you have an arrow 00:41:28.110 --> 00:41:30.930 that's truly telling you where the light will come on, an 00:41:30.930 --> 00:41:33.610 arrow that's misleading you, or an x 00:41:33.610 --> 00:41:34.430 that tells you nothing? 00:41:34.430 --> 00:41:37.430 Which do you think you'll be fastest? 00:41:37.430 --> 00:41:38.450 PROFESSOR: Where the arrow's pointing, right? 00:41:38.450 --> 00:41:40.290 Like, here's the answer, over here! 00:41:40.290 --> 00:41:41.620 OK, thank you very much. 00:41:41.620 --> 00:41:44.820 Which do you think you'll be slowest on? 00:41:44.820 --> 00:41:46.390 The dishonest arrow, right? 00:41:46.390 --> 00:41:48.510 The arrow says, look over here, look over here! 00:41:48.510 --> 00:41:49.520 And you're looking over there. 00:41:49.520 --> 00:41:50.130 And you go, oh no! 00:41:50.130 --> 00:41:50.890 It came on the other side. 00:41:50.890 --> 00:41:52.960 You lied to me! 00:41:52.960 --> 00:41:53.790 And the x is the middle. 00:41:53.790 --> 00:41:54.720 And here's the data. 00:41:54.720 --> 00:41:56.740 And it's a very simple experiment, right? 00:41:56.740 --> 00:41:57.610 How fast are you? 00:41:57.610 --> 00:41:59.220 This is reaction time just to push a button 00:41:59.220 --> 00:42:00.370 when it comes on. 00:42:00.370 --> 00:42:03.010 Here's the neutral condition in the middle. 00:42:03.010 --> 00:42:06.730 You're a little bit faster if it's an honest arrow. 00:42:06.730 --> 00:42:07.930 You're a little bit slower if it's a 00:42:07.930 --> 00:42:10.350 dishonest, misleading arrow. 00:42:10.350 --> 00:42:13.920 So now, you do this exact experiment. 00:42:13.920 --> 00:42:14.800 And I'll show you the data. 00:42:14.800 --> 00:42:19.850 And then, I'll simplify it for you with patients who have 00:42:19.850 --> 00:42:22.590 right sided damage, left sided neglect. 00:42:22.590 --> 00:42:25.790 And you can see as you look at these lines that the arrow can 00:42:25.790 --> 00:42:27.750 be honest or dishonest, and it can be on the 00:42:27.750 --> 00:42:29.400 left or right side. 00:42:29.400 --> 00:42:32.040 Now, if you were always bad on the neglected side, you go, 00:42:32.040 --> 00:42:33.170 well, that's not a big surprise. 00:42:33.170 --> 00:42:34.450 But here's a surprise. 00:42:34.450 --> 00:42:36.550 Patients were only bad-- 00:42:36.550 --> 00:42:40.950 the times were way up here only when they had a dishonest 00:42:40.950 --> 00:42:43.970 arrow that sent them into their good side. 00:42:43.970 --> 00:42:45.490 That's when they were really bad. 00:42:45.490 --> 00:42:47.130 So let's take a look at this again. 00:42:47.130 --> 00:42:48.780 So here's the bad side. 00:42:48.780 --> 00:42:50.070 Here's the good side. 00:42:50.070 --> 00:42:53.330 When that arrow comes on that's honest, good. 00:42:53.330 --> 00:42:57.990 When an arrow comes on that's honest this way, they do fine. 00:42:57.990 --> 00:42:59.400 That's their bad field, but they do fine. 00:42:59.400 --> 00:43:01.810 Tiny bit slower, but just a tiny bit. 00:43:01.810 --> 00:43:04.800 Arrow comes on that moves them into their bad field but 00:43:04.800 --> 00:43:06.930 really the light is on here, they do fine. 00:43:06.930 --> 00:43:10.970 But if an arrow sends them into their good field, then 00:43:10.970 --> 00:43:14.295 they're really, really slow to get back here. 00:43:14.295 --> 00:43:17.210 So Posner argued that when you move your attention in the 00:43:17.210 --> 00:43:20.150 world, you have three steps you have to do. 00:43:20.150 --> 00:43:22.270 You have to disengage your attention from where you're 00:43:22.270 --> 00:43:23.710 paying attention, just logically. 00:43:23.710 --> 00:43:25.340 I'm paying attention here right now. 00:43:25.340 --> 00:43:26.420 I'm going to pay attention over here. 00:43:26.420 --> 00:43:29.600 I have to pull myself up from here, move my attention over 00:43:29.600 --> 00:43:31.540 here, and then focus here. 00:43:31.540 --> 00:43:34.300 So you disengage, get out from where you are, move to where 00:43:34.300 --> 00:43:35.920 you need to go, and land and then focus 00:43:35.920 --> 00:43:37.300 what you want to do. 00:43:37.300 --> 00:43:40.600 And the only condition where they're bad is where they have 00:43:40.600 --> 00:43:43.680 to get their attention out of the good field as if once 00:43:43.680 --> 00:43:46.460 they're in that good field, once their mind is landed in 00:43:46.460 --> 00:43:48.660 that good field, they're in quicksand. 00:43:48.660 --> 00:43:51.100 And it's going to be really hard to get their attention to 00:43:51.100 --> 00:43:53.470 move into the bad field. 00:43:53.470 --> 00:43:54.520 So think about this. 00:43:54.520 --> 00:43:57.930 The clocks are perfect for this because when you draw a 00:43:57.930 --> 00:43:59.390 clock mostly-- 00:43:59.390 --> 00:44:00.900 think about that as intuitively-- 00:44:00.900 --> 00:44:03.460 if I was to ask you to draw the numbers on a clock, you 00:44:03.460 --> 00:44:05.320 start with a 12 typically. 00:44:05.320 --> 00:44:08.070 Then, what's the next one you would draw? 00:44:08.070 --> 00:44:11.180 One, because that's how we're taught to do clocks. 00:44:11.180 --> 00:44:13.330 Disaster if you have neglect. 00:44:13.330 --> 00:44:15.110 You're in the good field. 00:44:15.110 --> 00:44:18.550 Now, the left half of the clock has disappeared on you 00:44:18.550 --> 00:44:21.950 because the clock has made you land your attention on the 00:44:21.950 --> 00:44:23.260 good field. 00:44:23.260 --> 00:44:25.730 And now, you can't pull out of it. 00:44:25.730 --> 00:44:29.350 But what happens if you only have to draw 8 o'clock? 00:44:29.350 --> 00:44:31.930 Your attention never got moved into the good field. 00:44:31.930 --> 00:44:34.200 It's just starting from middle, so to speak. 00:44:34.200 --> 00:44:36.980 And this very same patient can draw the 8 o'clock or 10 00:44:36.980 --> 00:44:38.220 o'clock pretty well. 00:44:38.220 --> 00:44:39.710 Does that makes sense? 00:44:39.710 --> 00:44:43.340 Because they never got stuck in the good field. 00:44:43.340 --> 00:44:45.400 They only moved into the bad field. 00:44:45.400 --> 00:44:47.340 They can move into the bad field. 00:44:47.340 --> 00:44:51.040 And so if their eyes are closed, that's better. 00:44:51.040 --> 00:44:52.260 They get less stuck. 00:44:52.260 --> 00:44:53.630 And now, we understand this thing. 00:44:53.630 --> 00:44:56.210 Why is it these patients, if both fingers are moving-- 00:44:56.210 --> 00:44:58.230 because once their attention is drawn into the good field, 00:44:58.230 --> 00:45:00.160 it's as if the bad field disappeared on them. 00:45:00.160 --> 00:45:04.370 But if they only get stimulated in the bad field, 00:45:04.370 --> 00:45:08.820 so right side here, then they're OK because they never 00:45:08.820 --> 00:45:11.580 paid that much attention to the good field. 00:45:11.580 --> 00:45:12.445 So this is a nice experiment. 00:45:12.445 --> 00:45:14.240 It shows you what is the problem. 00:45:14.240 --> 00:45:17.100 The problem is once you're paying attention to the good 00:45:17.100 --> 00:45:20.730 field, the normal, healthy field, it's so powerful 00:45:20.730 --> 00:45:22.500 compared to the weakened representation here, that you 00:45:22.500 --> 00:45:24.440 never leave it because it just seems like everything. 00:45:26.980 --> 00:45:29.420 Now, here's a clever one. 00:45:29.420 --> 00:45:32.620 Again, this shows you how much of attention is created by our 00:45:32.620 --> 00:45:36.570 minds as opposed to just simply defined by the 00:45:36.570 --> 00:45:37.410 environment. 00:45:37.410 --> 00:45:41.350 So what if you show a display to somebody with neglect and 00:45:41.350 --> 00:45:45.850 then rotate the display right in front of them? 00:45:45.850 --> 00:45:47.860 So initially, the neglect is going to be on the left side. 00:45:47.860 --> 00:45:50.520 But imagine the thing is turning over like this, right 00:45:50.520 --> 00:45:51.460 in front of them. 00:45:51.460 --> 00:45:55.590 Will the neglect travel with the initial assignment? 00:45:55.590 --> 00:45:57.790 So this is from Marlene Behrmann, a very clever 00:45:57.790 --> 00:45:58.370 experiment. 00:45:58.370 --> 00:45:59.530 They have to pay attention if the light 00:45:59.530 --> 00:46:00.930 comes on here or here. 00:46:00.930 --> 00:46:03.180 But what they do is while the experiment's going on, right 00:46:03.180 --> 00:46:06.000 in front of you, it slowly rotates over to here. 00:46:06.000 --> 00:46:08.300 And sure enough, then the light comes on. 00:46:08.300 --> 00:46:13.180 Sure enough, the neglect now moves into the good field 00:46:13.180 --> 00:46:15.509 because once you've assigned left and right, you 00:46:15.509 --> 00:46:17.300 know this is left. 00:46:17.300 --> 00:46:18.840 So OK, you turn it over. 00:46:18.840 --> 00:46:21.340 That's still really left. 00:46:21.340 --> 00:46:22.340 But think how weird that is. 00:46:22.340 --> 00:46:23.790 The mind is deciding that. 00:46:23.790 --> 00:46:26.720 In an absolute sense, this thing is on the right. 00:46:26.720 --> 00:46:28.600 But the mind said, this is the leftward one. 00:46:28.600 --> 00:46:31.780 And you can flip it over, but you're not tricking me. 00:46:31.780 --> 00:46:33.940 I know it's on the left, and I'm considering it the 00:46:33.940 --> 00:46:35.360 leftward one. 00:46:35.360 --> 00:46:37.370 The mind is deciding what counts as left and 00:46:37.370 --> 00:46:40.830 right, not the world. 00:46:40.830 --> 00:46:44.370 And what other kinds of information is being processed 00:46:44.370 --> 00:46:47.190 that's not reaching attention levels? 00:46:47.190 --> 00:46:50.070 So here's a cute experiment. 00:46:50.070 --> 00:46:53.930 They would say to these patients, any difference 00:46:53.930 --> 00:46:55.200 between these two things? 00:46:55.200 --> 00:46:56.940 No. 00:46:56.940 --> 00:46:58.920 But if you had to live in one of these houses, which one do 00:46:58.920 --> 00:46:59.580 you think you'd live? 00:46:59.580 --> 00:47:00.170 Well, I don't know. 00:47:00.170 --> 00:47:00.800 They're pretty much the same. 00:47:00.800 --> 00:47:01.460 Why would I pick one? 00:47:01.460 --> 00:47:02.810 Well, pick one! 00:47:02.810 --> 00:47:04.900 They go, ah, this looks like a little better place to live if 00:47:04.900 --> 00:47:06.280 I have to pick one. 00:47:06.280 --> 00:47:07.690 Which vase do you want? 00:47:07.690 --> 00:47:08.070 I don't know. 00:47:08.070 --> 00:47:08.880 They look the same. 00:47:08.880 --> 00:47:09.590 You have to pick. 00:47:09.590 --> 00:47:11.350 I pick this one. 00:47:11.350 --> 00:47:13.180 Which glass to drink from? 00:47:13.180 --> 00:47:14.140 You have to pick. 00:47:14.140 --> 00:47:14.430 Pick this one. 00:47:14.430 --> 00:47:17.640 So they consciously are not aware of what's going on here 00:47:17.640 --> 00:47:19.560 when there's information to the opposite side to draw 00:47:19.560 --> 00:47:20.410 their attention. 00:47:20.410 --> 00:47:22.570 But something in their mind somewhere is picking up 00:47:22.570 --> 00:47:23.670 information. 00:47:23.670 --> 00:47:25.870 So the last question-- and I'll show you a final video-- 00:47:25.870 --> 00:47:26.690 is this. 00:47:26.690 --> 00:47:29.450 What kind of information is picked up in the neglected 00:47:29.450 --> 00:47:33.700 field as you decide, some part of your mind, to neglect it? 00:47:33.700 --> 00:47:38.240 So imagine if I showed you two forks versus 00:47:38.240 --> 00:47:39.490 a fork and a spoon. 00:47:42.520 --> 00:47:45.710 In order for that to make a difference whether you report 00:47:45.710 --> 00:47:47.890 both are present-- so again, if you have a right sided 00:47:47.890 --> 00:47:50.480 lesion, you might tend not to report this fork or not to 00:47:50.480 --> 00:47:52.250 report this key. 00:47:52.250 --> 00:47:55.650 If you just don't report either one, OK, left is left 00:47:55.650 --> 00:47:56.870 and you're bad at reporting that one. 00:47:56.870 --> 00:47:58.650 There's something competing in the good field. 00:47:58.650 --> 00:48:02.560 Your attention gets drawn here, hard to disengage. 00:48:02.560 --> 00:48:06.690 But if it makes a difference what this thing is, that means 00:48:06.690 --> 00:48:09.920 that your mind kind of knows what it is. 00:48:09.920 --> 00:48:13.980 And your mind is saying, well, if it's a key, that's 00:48:13.980 --> 00:48:15.930 different enough that I can still pay attention to it. 00:48:15.930 --> 00:48:19.240 But if it's another fork, those are really similar. 00:48:19.240 --> 00:48:21.820 And now, my mind is really sucked into this fork. 00:48:21.820 --> 00:48:24.020 But in order for that to make a difference, do you see that 00:48:24.020 --> 00:48:26.650 you have to know somewhere in your mind what's different on 00:48:26.650 --> 00:48:28.680 the left for that to affect your performance? 00:48:28.680 --> 00:48:31.880 So now, we'll see a video of a patient, the last one. 00:48:31.880 --> 00:48:36.270 This is a neurologist, Bob Rafal, and a patient. 00:48:36.270 --> 00:48:39.150 It's a hugely nice thing of the patients, most of all, but 00:48:39.150 --> 00:48:41.590 also the physicians to make these tapes available for 00:48:41.590 --> 00:48:42.840 teaching purposes. 00:48:48.920 --> 00:48:50.380 So you understand-- 00:48:50.380 --> 00:48:52.420 just review for one month and we're done-- 00:48:52.420 --> 00:48:55.470 that when the same object came up, did he pretty much notice 00:48:55.470 --> 00:48:57.730 the one on the bad side and the right side for him? 00:48:57.730 --> 00:48:58.600 No. 00:48:58.600 --> 00:49:00.840 Same object, he almost always said it's one. 00:49:00.840 --> 00:49:03.850 If they're different objects, he typically reported slightly 00:49:03.850 --> 00:49:06.560 sluggishly the one on his bad side. 00:49:06.560 --> 00:49:10.340 That means part of his mind has to know what the object is 00:49:10.340 --> 00:49:14.700 so that he ignores it if it's identical and he reports it if 00:49:14.700 --> 00:49:15.300 it's different. 00:49:15.300 --> 00:49:17.390 Well, you have to know what it is to base 00:49:17.390 --> 00:49:18.660 your answer on that. 00:49:18.660 --> 00:49:22.490 Yet, the logic of neglect is that if they're identical, 00:49:22.490 --> 00:49:24.710 then he's going to ignore the one that he spotted on the 00:49:24.710 --> 00:49:28.300 left in part of his mind but squashed from his awareness on 00:49:28.300 --> 00:49:29.085 the other side. 00:49:29.085 --> 00:49:30.335 OK, thanks very much.