Sense Perception (1960)

[Music] hello there a hearty welcome to Moody Institute of science for several years here at the laboratory we've been studying the human senses and the deeper we go into the subject the more fascinating and wonderful it becomes as we explore the mysteries of sense perception together we're going to have a lot of fun there'll be some surprises and quite a few Chuckles but also we're going to discover that there is real significance in the study how many senses are there well more than the traditional five a lot more but it's not without reason that these five have been called the windows of the soul the sense of sight which opens to us all the beauty and wonder of the world around us the sense of hearing and the many voices of the [Music] world the sense of taste with its endless Delights oh yes and that wonderful sense of [Applause] smell the sense of touch with hands both young and old viewing the senses individually we find that they are wonderful indeed but our senses don't function independently they operate together as a team forming a smoothly integrated complex electronic system let's watch this system work at a baseball game nice catch but let's take a closer look at the electronic magic behind that catch at the instant the ball was hit countless bits of information were flashed to the outfielder's brain his eyes told him the the angle at which the bat hit the ball and the direction it was starting to travel his ears told him how squarely and how hard the ball was hit his sense of touch gave him Clues as to wind direction and velocity and from his memory came thousands of Clues gained through past experience this information was combined to solve a complex problem involving geometry trigonometry calculus and ballistics and he makes the catch in a single day of normal activity it is probable that the sensory system of your body will handle more messages than have been carried by all the Telephone and Telegraph lines of the whole world during the past 50 years the human senses are wonderful and they serve their intended purpose as well but the world around us they are extremely Limited let's take the sense of sight for example now our eyes are sensitive to a particular range of frequencies which we call visible light but visible light is merely a small part of the electromagnetic spectrum which includes electric waves radio waves infrared ultraviolet x-rays gamma and cosmic rays now in a very real sense all of this is light but nearly all of it is light we cannot see these frequencies have special meaning for us merely because they are the ones to which our eyes will respond now of course electric waves and radio waves have different properties because they're different wavelengths but that same thing is true of any part of the spectrum even in the visible spectrum there are different wavelengths which have different properties in the electromagnetic spectrum the longest waves are the electric waves which commonly supplies us with Power electric waves are some 3,000 m in length but as they become shorter and vibrate faster they gradually merge into radio waves the longer radio waves we pick up on our standard broadcast receivers for shorter waves we have to use shortwave receivers television sets various radar systems but as the waves become shorter and vibrate still faster we move into the infrared section these waves cannot be tuned in on our radio or TV sets instead we tune them in on our bodies and call them heat wavelengths of invisible infrared light are so close to the longest waves of visible light that often both can be detected at the same time moving across the visible spectrum the waves become shorter and vibrate faster until finally visible Violet disappears into invisible ultraviolet sometimes called black light now ultraviolet rays are too short and vibrate too fast for the human eye to see but there are ways we can see their effects sunburn for instance is caused by invisible ultraviolet light some minerals can change invisible ultraviolet light into frequencies we can see rather ordinary looking aren't they well now let's shine some invisible ultraviolet light on them instantly they flame into glowing Beauty as short waves of invisible ultraviolet light are sent back as longer waves which we can see traveling farther down the Spectrum we come to X-rays of course our eyes are not sensitive to x-ray light but photographic film is a fact made use of every day in medical laborat teritories so in reality we who think we see so much are groping around in a world Ablaze with glory and wonder and light and color and we're almost totally blind now does this mean that our sense of sight is any less amazing and wonderful than we had supposed not at all it merely means that the Universe around us is infinitely more wonderful than anything of which we've ever dreamed all of us have heard someone say I will not believe in anything that I cannot see with my own two eyes well the very least that you can say about such a person is that he must have a narrow view of the world around him yes our vision certainly is limited but how about the sense of hearing is it also limited well did you ever hear one of these quiet isn't it no not really this is an ultrasonic dog whistle actually the sound is very loud a dog can hear it all over the neighborhood but it's beyond the range of the human ear now we've built a super high powered dog whistle in the science laboratory it's called a gton whistle after Sir Francis gton who invented it the whistle is now blowing full blast though completely inaudible to us it is a tremendous intensity in fact it is so loud that the sound can actually be used to support objects in midair the Silent Sound from the whistle is bounced back and forth to form a standing wave pattern these waves whip the air molecules into a stormy sea of violent motion except at two points in each wave it's at these points or nodes that the cork chips are suspended this world of Silence sound brings man face to face with a realm far beyond the narrow limits of the human senses now before the molecular nature of matter was known the sense of smell and to a lesser degree that of taste were almost a complete mystery knowledge however has not lessen the Wonder of these so-called chemical senses it has merely enabled Us in some small degree to appreciate their Wonder now any substance is composed of invisible particles called molecules these particles are in continuous movement in some substances the movement is so violent that particles near the surface go shooting off into the air this is what gives a substance an odor dramatic proof of this may be had by by pouring some mercury into a dish and then carefully sprinkling the surface of the Mercury with a fine powder now if we bring a substance with a strong odor close to the surface of the top the powder will be pushed violently Away by the invisible particles coming from the substance [Music] a man has devised instruments so sensitive that they can detect one part of a substance in 10 million parts of air your old factory organs however can detect one part in a thousand million but compared to that of many animals man's sense of smell is quite limited the Blood Hound for instance has the extraordinary ability to follow a scent when its hours or even days old but perhaps the most limited sense of all is the sense of taste yes even the man who prides himself on a very discriminating sense of taste is limited like the rest of us to just four kinds of taste buds salt sweet sour and bitter did you know that if a person is blindfolded with his nasal passages completely blocked he can't tell the difference between an onion an apple a pear or a potato it's a fact it's only the odor that makes the flavor different as we began our study of the mysteries of sense perception one of the first things we had to recognize is the fact that we do not see with our eyes or hear with our ears these are merely the external receptors the real seat of sense perception is in the brain it is here that we see and hear and detect odors and taste our food and otherwise sense the world around us and it's a good thing that this is so for example if seeing we're done only in the eye everything would be upside down to us the eye is actually a miniature camera just as in a camera the lens of the eye forms the image upside down the image is then in inverted by the brain so that it appears right side up now what would happen if a lens system were used to form the image right side up well the brain would immediately invert the image so that it would be upside down but would this condition be permanent to answer this question we asked Mr Gratz our Optical expert to design for us a pair of inverting spectacles while the spectacles were being constructed in our shop we faced the problem of who was going to wear the things continuously for several weeks so we decided to have an election and now you'll want to meet our unlucky winner that's right me even from the first it was possible to walk in this Topsy Turvy fashion but it didn't take long to develop a rolicking case of seasickness we decided that for your sake as well as ours we'd better conduct our first test sitting down however just sitting down wasn't so easy even the simplest tasks were at first impossible no amount of concentration or effort could overcome the compulsion to reach in the wrong direction the inverting spectacles had to be worn every waking moment during the entire period of the experiment anytime the glasses were removed the eyes were closed or fully covered walking to work upside down was an exhausting experience but it provided a valuable period of relearning and reorientation it also caused quite a stir in the neighborhood gradually it became easier to get around in this upside down World by a slow and painful process the image in the brain had been erected at this point we decided to devise a convincing demonstration showing that reorientation had been achieved the test with the motorcycle went so well that we decided to extend the experiment to Flying an airplane where visual coordination and depth perception are even more [Music] critical the flight lasted more than an hour during which all normal flight Maneuvers were executed [Music] [Music] in performing the experiment with the inverting spectacles we became very much aware of how important it is that seeing is done in the brain not just in the eye when you look at a brick wall for example staring straight ahead with one eye closed there is a hole in the picture image sent to your brain the hole is irregular in shape and occurs 12° to one side however try as you will you won't be able to see the hole your mind will fill in the missing detail Brick by Brick but why is the blind spot there in the first place the answer lies in The Amazing construction of the eye the inner curved surface at the rear of the eye called the retina is a fantastic thing its function is to transform a visual image into electrical impulses which are collected by a network of more than one million tiny nerve lines which carry the visual image to the brain the blind spot occurs at that point in the retina where the nerve lines join the optic nerve at this point there are no seeing elements now it's a good thing that this spot is not in the center of the retina for if it were our vision would have been seriously impaired as it is however the hole is always there in the image centered the brain but the brain always fills in the hole with detail similar to that which surrounds it but someone says well maybe I don't see everything around me but if what I do see I see correctly I'll still trust my senses well recently there has been a great deal of careful research and study into the subject of the accuracy of the senses and uh the results have been quite amazing the scientist adelbert Ames has developed some ingenious experiments in this figure the two ends obviously are parallel but the two sides are not parallel because the two ends are not the same length this figure we call a trapezoid now let's remove the cover are you you a bit confused well all we've done is cut some holes in the figure and painted it to look like a window frame but maybe you say well you can't fool me that's still a trapezoid well it's still a trapezoid all right but now let's revolve the figure and see what happens does the window frame seem to turn then stop and reverse directions well such is not the case it is revolving continuously in a clockwise Direction now even when we know this the illusion still persists and it looks more like a window all the time well maybe you need a reference point see if the cube will help you follow the edge of the trapezoid all the way around watch closely now doesn't help a bit does it not only does the trapezoid still oscillate back and forth but the cube actually seems to take off and go floating through space now it doesn't of course actually the cube has been firmly attached to the edge of the figure all the time now an iron bar should make a good solid reference point let's see what happens now when we rotate the window of course we know that the revolving window frame cannot possibly bend the iron bar or cause it to cut through the window frame but this knowledge seems to be of no help at all the illusion of an oscillating window still continues from earliest childhood it has been our experience that windows are rectangles and that all sides are parallel your eye sent an accurate image to the brain the image of a trapezoid painted like a window but your mind said Ah that's a window and rather than give up the idea that all windows are rectangular your mind accepted all sorts of improbable things solid bars bending or cutting through solid matter without even leaving a hole we emphasize the fact that seeing is done in the mind not just the eye and I think you're beginning to see the importance of this emphasis but adelbert Ames had some other experiments which were most revealing now as I step into this room it should be quite obvious that something is wrong but can you figure out what it is your mind may tell you that I have grown smaller of course you know know that that really isn't true your eyes however are telling you the truth they're telling you that the floor is tilted up that the ceiling is tilted down that the walls are badly distorted that the windows be almost impossible to make drapes for them yes your eye is telling you all this but your mind simply refuses to believe it but maybe this will help imagine all of this without benefit of vitamins but it also works the other way too now if you'll just step back a bit you'll see the real cause of the trouble it's quite obvious at this distance isn't it sloping floor tilted ceiling distorted walls but uh since you understand this you shouldn't have a bit of trouble from now on should you or should you in this this house faces at the window seem to come in assorted sizes don't they but uh there's nothing wrong with the faces it's those windows and what they're doing to your brain remember a small one and a tall one let's see if we can even things out a bit oh no that's even worse it comes as a distinct shock to most people when they realize how limited and how inaccurate the human senses really are now of course the scientist is keenly aware of these limitations in fact this awareness is the very Foundation of modern science before the age of science man had no real concept of an orderly Universe governed by unchanging law he proudly built his theories and philosophies on the meager scrap STS of information coming from his limited and inaccurate senses this was a time when Alchemist mixed their magic potions when astrologers tried to predict the future when fryologist measured bumps on the head to gauge a man's intelligence but about 300 years ago the picture began to change the age of science was born when man quit trusting his senses and developed instruments to overcome their limitations today man knows that the physical world is governed by Universal and unchanging law that has been operating since time began man knows that there is Rich reward for strict detailed obedience to physical law and also a Stern penalty for Disobedience he knows that sincerity and good intentions are not enough now this attitude in the scientific realm is relatively new but it certainly has paid off as soon as man adopted this attitude there was a sharp upturn literally an explosion in scientific progress and yet with all the potential for good this scientific development has brought man face to face with the greatest crisis in human history and why do we face this crisis is it because scientific knowledge has grown too rapidly and too extensive l no not at all obviously scientific advancement must continue it would be both foolish and dangerous to lag behind and yet it would be far more foolish and dangerous to lag behind in our capacity to use this knowledge wisely we must develop a sense of moral and spiritual responsibility so that the fruits of scientific progress may be devoted to life instead of death now if man is to survive man must change in other words there must be a moral and spiritual breakthrough every bit's revolutionary is the one we've experienced in science and I'd like to suggest that such a breakthrough is entirely possible and that both the problem and the solution have a definite parallel in the history of Science Now for thousands of years there was virtually no no scientific progress and then suddenly something happened there was literally an explosion in scientific development and the curve is getting steeper all the time but what caused this change well obviously the physical Universe didn't change suddenly and we can't explain the situation by saying that man is smarter now than he was then his IQ is probably very much the same there was however a very very basic change in man's attitude during this period man was committed to trusting his senses and the result virtually no scientific progress but then man woke up he began to search out the laws of the physical universe and as fast as he discovered them he obeyed them he accepted their restraint and their discipline and for the first time in history he was free free from bondage to ignorance and Superstition and unworkable philosophies and theories and the result an explosive progress but how about the moral and spiritual realm in this realm man seems to feel that there are no absolute values and no fixed laws so once again he is committed to trusting himself his own ideas his own theories and philosophies and what's the result virtually no progress now judging from our experience in the scientific world it would seem that once again we're on the wrong track but let's suppose that the young people of today recognize the need for a breakthrough in this the most important realm of all let us suppose that they recognize the existence of absolute values and fixed laws and that they set themselves to obeying those laws with with all of the dedication and the honesty and the energy which they bring to the scientific task what will be the result an explosive change a surge in moral and spiritual strength to match our progress in science and to give meaning and purpose to our lives