April 17, 2004

• I mean, on the one hand, it makes perfect sense. I should use visual clues to help determine what people are saying if I can see their face. That's why it's easier to understand someone who's talking to you face to face, rather than over the phone. On the other hand, if I know for a fact that he's saying "Ba," I expect my brain to get with the program! But it does not. I'm obviously going to have to have a stern talking to with my brain.
• Sorry to bring up another forum, but exactly what I predicted elsewhere.
• The self, where your senses converge and your intent diverges.
• Your tax dollars (kroner) at work.
• it's very, very strange. this is the first "audio illusion" i've seen (well, heard). the superior and inferior colliculus of the brain are part of the mesencephalon (middle brain), (labeled 1 and 4, respectively, in this photo, if you want to see one). they lie near the back of the brain, sandwiched between the cerebellum and the visual processing portion of the cortex. what the colliculi do is to integrate visual (superior) and audio (inferior) input to the brain. primarily, this involves localizing sounds or movement - imagine a cat when it spies something, or hears a sound - the whole body orients towards the source. the colliculi take this audio or visual input and coordinate this with input and output to other parts of the brain, resulting in actions like orienting your head to better hear or see something. apparantly this "audio illusion" messes with this integration system by giving the superior and inferior colliculi conflicting information. your audio system reports that it's hearing "ba", but your visual system reports that it's seeing "ga". the colliculi dutifully integrate this informaiton and report back to everything, sort of averaging the signal and the net result is that you hear/see "da" (although it seems sort of muddled). this is thus different from a standard optical illusion, which merely takes advantage of the way in which we process visual signals to produce something that isn't there (much the way that a string of rapid still images will look to us like a moving picture - just an optical illusion, but without that we'd have no TV). this uses two systems to generate conflicting info, in which case the brain kind of says "um... it's both!" (oh and i have no proof that this is really how the McGurk effect works - just given what i know about brain anatomy & function it seemed like the most logical thing to assume... tell me if i'm wrong, anybody)
• No matter what I did, as long as I was looking at the video I could not persuade my brain to hear "Ba" at all. Very, very odd and cool. At first I assumed I was hearing "Da" because I read the blurb before listening, but it didn't matter how hard I tried as long as I was watching the guy talk. As soon as I looked away, though, "Da" turned into "Ba". Awesome find. It's amazing how our brain perceives our reality.
• I love C.L. Frogs. I thought I might know enough about brain anotomy as relates to language skills from my BioAnth studies, but no, oh no no no no no. Frogs very much be the man. Can't be demonstrated via the means of webbery, but I love the example Francis Crick mentions in The Astonishing Hypothesis. People who are blind, but don't think they are. They fill in appropriate physical details from what their other senses can pick up about an environment, and then just deny all the inexplicable anomalies. For example, if the experimenter says, "What colour tie am I wearing?", and they say "Red,", and the experimenter then (correctly) states that he's not even wearing a tie, the subject will say something like, "Oh, must have been a trick of the light," or something similar; they have no idea that they're blind, and will talk away tripping over chairs they don't know are there as something to do with shadows... The human brain is fucking weird as shite. Brilliant...
• ...anatomy...
• Gaga is as gaga doesn't, it seems. Interesting and strange.
• That was fascinating. I must be something of an anomaly though - I didn't hear "da" at all - I heard "ga" - or rather something like "nga". Until I looked way or closed my eyes, that is. The fun part is that if you look away from the screen and look back again, you hear "Ga ga, ba ba [looking away], ga ga".
• It's just... weird... when your brain is fully aware that another bit of your brain is being a total pillock. And yet the bit of your brain that knows you're being daft can't do anything to stop that perception happening. Never trust a human (assuming they have a human brain). Just doesn't work...
• Yes, jb, ga is what I heard, too. Also sounded like it was coming out of the wrong part of the mouth, not a frontal ga-sound, but too far back in the throat, as if under the uvula.
• i think you are on to something, beeswacky. i must google this journal citation, but i wonder if it is something to do with linguistics and/or phonics. in the video the mouth is forming a gutteral. the actual sound and the perceived sound are markedly different to the perceiver. the 't' and the b' and the 'g' are all formed in different areas of the mouth and positioning of the tongue. then, also, each sound is a homorganic symbol with many similarities. i couldn't hear the 'ta' sound but i had read the commentary first.
• exactly what I predicted elsewhere. I'm sorry, but predicting the result of experiments that were carried out in the 1970s is just not really that useful. I am predicting a terrible war to start somewhere around 1939, myself. Anyone want to second me?
• I don't believe you, Wolof. Next thing you'll be wanting us to believe is that the English would up and cut off their king's head in 1649.
• Wolof, 1)I did not posit utility. 2)I did not know of the effect at the time I made the prediction. The next poster brought it to my attention. If you choose to not believe me, that's your prerogative. jb, about the inability to "not do anything about it", without getting philosophical, effugas at MeFi points out: "The McGurk effect probably has alot to do with the fusion of sensory signals at the LGN -- the laternal genticular nuclei. Basically, our optical and auditory nerves merge at this small nut shaped region, and are joined by nerves from all over the rest of the brain. IOW, there are feedback loops that modify our sensory signals _before they're even analyzed_. Thus the very strongly perceived auditory shift based on lip motion -- I mean, it's not just that we understand differently, it really feels like the voice says something different when we close our eyes."
• If you choose to not believe me, that's your prerogative. Of course I believe you. I'm only pointing out that you want to be careful around words like "predict", especially when the literature is already out there to be read. Also, I'm being a dick because I read the Nature article on McGurk several years ago, but couldn't use it in my thesis (on the nature of the audio-visual contract) other than to debunk some French researcher's interpretation of it. So I decided to junk the whole section. This goddam effect owes me!
• Wolof, I used 'predict' to communicate the results of my agency, I don't see the need to be careful over that. I might as well say I don't remember my name. Nonetheless, it's allright.
• err.. allright wasn't alright.
• All right, then.
• gyan - i'd believe that except LGN (lateral geniculate nuclei) don't do much except relay visual info. as far as i know no auditory signaling, but they recieve direct retinal input en route to the visual cortex. part of my thesis focuses on a small section of the geniculate complex and how it relays signals back to the circadian system. if there's a lateral "genticular" nucleus i've not heard of it. i imagine that's a typo. could be wrong, though. this diagram shows both the pathway from eyes through the LGN to the visual cortex. inset (bottom) shows the location of the superior / inferior colliculi - note that these are a separate pathway, bypassing the LGN. and thanks for the banana flashboy!
• Sorry I'm late (as usual). I find that when looking at the clip, I heard "da", but if I really concentrate and argue with my brain, I can hear "ba" even while looking. But once I stop concentrating, I hear "da" or even "ga".
• I put the clip in da ba gua prosperity corner.
• Wolof: You mean you have a BIG octotrigram? Does it come with a mirror?
• Oh yeah, "I see a voice".