GATEWAYS TO THE MIND

[music] [music] Doc, before you get to the science of how we see, I'd like to introduce you to the big eye. Well, it's true. The human eye has often been compared to the workings of a camera. You step right this way, doc. Now, suppose we start with a lens. You can see inside the sunbox. The light coming through the lens is focused on the film. Now, this is the iris and we can regulate the way it opens and closes to admit various degrees of light. Now, suppose we look at the side. Now the film moves down here where the light coming through the lens strikes it. So this is where the negative is exposed. Yes, that's right. Hal, your camera is a fine machine for taking moving pictures. Now let's look at something much more remarkable. This is a closeup of a normal human eye. The periodic blinking of our lid keeps the outer eye surface moist. Up under the lid and at each corner of the eye are tiny glands manufacturing tears which wash away dirt particles [music] and contain an antibiotic to combat germs. The iris opens and closes automatically to control the amount of light admitted through the pupil to the inner eye. Ever wonder what a doctor sees when he looks inside your eye? Well, here it is. The retina. the only place in a living man where some of his nervous system can be seen. This part of the eye compares to the film in the camera. It's on this delicate screen that all objects of our vision are transformed into myriad electrical impulses. This is the blind spot where [music] the nerve fibers of the retina come together to form the optic nerve which bundles them out to the brain. There are no light receptors at this point. So it is literally a blind [music] spot. Now in this diagrammatic side view, light reflected from an object strikes the [music] transparent surface of the eye, the cornea. The iris opens or closes to the correct aperture. The light passes through the lens which brings it into focus on the retina. This curved screen contains over 125 million tiny light sensitive cells, each capable of dispatching an individual message to the brain. In this photo microraph of the cross-section of the retina, [music] we can actually see some of these cells. This depression is the phobia. Here we have our sharpest vision concentrated in an area the size of a pin head. This is the visual center of the eye. Looking at something means [music] catching its image on the phobia. We have two kinds of light sensitive cells, cones and rods. The cones in bright light transmit our color vision. In dim light, they cease to work and the rods take over. Rods transmit our vision only in black and white. This is why, as daylight deepens into dusk, colors dim and fade away. Here's a diagrammatical closeup of the rods and cones. Each rod and cone is sensitive to light because of a pigment contained in its tip. When this colored substance is struck by [music] light, it's chemically changed. This excites the nerve, sending messages to the brain which enable us to see. This then is the human eye, an organ which inspires poets as well as scientists. For it is the eye that gives us the colorful, everchanging world of vision. In order to examine the last of Aristotle's five senses, the sense of touch, let's drop in on this gentleman to whom we have already been introduced. Return again to that road map of his sensory system and out to that suburb we visited before. And it's a well populated place because in one tiny area we find not only the sense of touch but at least four other senses. These are true senses just like Aristotle's major five for each has its own signal system and nerve endings that can be individually identified. For example, these are the free nerve endings of pain. There are millions upon millions of these tiny filaments throughout our bodies. Well, Jean, why don't you try one of your real life dramas to show how this team of senses operates? Okay, let's take the situation of a lady testing a hot iron. Bill here has consented to add the exacting role of housewife. I'm one of those modests to science you hear about. Okay, let's run through the whole act. Oh, bravo. And here's the way it works now in slow motion. When the tip of the finger touches that hot surface, a number of things happen and happen fast. Hundreds of pain endings charge into action. Touch [music] sends out information on surface conditions. Heat and cold report the temperature changes on the skin. Pressure reacts to the sensation of [music] finger against iron. So these sensory messages race up the finger and the arm and reach the spinal cord where there's something like [music] um oh an automatic switchboard where pain triggers an immediate reflex action as well as continuing to the brain. Now the reflex signal races back and activates [music] the muscles of the arm and the finger is jerked away from the iron. And it's only when the other sensory messages report in on the master receiver and the pain impulse finally reaches the phalamus that [bell] our little man knows the finger has been hurt. Well, isn't it true doctor that some people are more sensitive to pain than others? Oh yes. Yes, that's very true. People differ greatly in this. Doctor, when you sit down. Thank you. really enormous variations in what we call the threshold of pain. Some people are born with no sense of pain at all. No toothache. That bad? Was really very serious to touch a hot iron, cut yourself badly, and feel no pain. Imagine a child who would have to be watched every second because he would never know when he'd hurt himself. What about the other senses, Doc? Sense of humor, sense of balance, common sense, horse sense. Well, these are everyday expressions, common places, figures of speech, except the sense of balance. And that's a very real sense. Without the sense of balance, you couldn't stand up. Certainly, you couldn't walk. And behind this sense of balance is a most interesting mechanism. Within the inner ear, we have the semic-ircular canals which are filled with liquid. Associated with the lining of these curved channels are minute hair cells. Now, it's generally believed that when we move our heads, the liquid disturbs these hair cells which send signals to the brain. We also have sense receptors in our muscles and tendons to tell the brain of any change in muscle tension. When Bill stands on one foot, he can feel this automatic interplay of the different muscles of his leg. And of course, his eyes tell him what he does. Coordinating all of this information from ears, muscles, and eyes at assembly points, the nervous system sends back reflex motor impulses to the right muscles, telling them to tighten or relax to keep the body in balance. This automatic feedback between the incoming signals and the outgoing compensating actions is what enables a cat to land on its feet or an acrobat to spin through the air to a precise landing. Now in slow motion, we can see what happens when a cat is dropped from an upside down position. His eyes and equilibrium organs in his ears cause him to write his head. This puts an uneven tension on the neck muscles and their tension receptors excite reflexes which [music] bring the body back into alignment with the head. Like the falling cat, we too are constantly getting sensory reports which themselves induce the next motion. This series of reflexes involving what is known as feedback results in controlled and accurate motion. Hey Doc, what have they got to say about tickling? Well, seriously, some physiologists say that tickling should be considered a real sense. I'd like to see you make a character out of that one. You know, the more we talk about the senses, the more characters we seem to be getting. It's getting to be like a regular three- ring uh circus. Yeah. Tada. [music] [music] [music] Heat. Heat. [music] Heat. Heat. Heat. Heat. [music] [music] [applause] [music] [music] seems to stop and and go back again, but it doesn't. It goes all the way around. It's an optical illusion. But even though you you tell me, my eyes still won't believe it. Well, let's attach a bar to the framework and see what'll happen. The trapezoid still appears to move back and forth, but the bar goes around. No, I'm really mixed up. Well, let's move up to an overhead view and see what happens. Plainly, it does go all the way around and the bar moves with it. Reason we are fooled from this angle [music] is that the trapezoid and its windows are not rectangular in shape, but we expect them to be because we have learned by experience that windows are rectangular. And even though we know it's turning all the way around, our brain still interprets the visual image in terms of past experience. [music] The yellow scarf hung on a short wire from one end of the trapezoid moves around in a ghostlike circle. While again, in spite of what we know, the window seems to stop, move back and forth. [music] [music] [music] I'll never trust another trapezoid. Now, let's go to Princeton University where the trapezoid experiment and others relating to perception and past experience were done. It's here in the demonstration laboratory that these windows were constructed. Why do the two heads seem to change size? Answer: The windows are distorted and this appears to be a normal room. Man, watch now. The man and boy are greatly distorted in size. The answer is obvious if we look at the room from another angle where we see that the room is distorted and the people are normal. Professor Hadley Canantrol Princeton psychologist can tell us the significance of what we have seen. The demonstrations you have just seen were devised by the scientist Adelbert Ames. While they are amusing illusions, they are much more than that. For they demonstrate some rather profound psychological principles involved in all of man's experience. They show that our experience is much more than a simple reaction to something outside and that we have to learn through our own past behavior the significance of the impressions our sense organs bring to us. And again this leads us to understand that the world we know is created in large measure from our past sensory experience. An interesting experiment that shows how the brain reacts to sensory stimulation can be shown here on the oscilloscope. And this instrument can be used to detect the impulses that reach the brain from the sensory organs. Now this brain is resting and the pattern of response is smooth. But if the eyes are suddenly stimulated by a flashlight, we see a violent variation in the pattern. Now let's observe what happens when a sudden loud noise is heard. So outside stimulation activates the brain. The screen's ready, doctor. Thank you. We wonder how human beings would react in situations where there was a near absence of things happening. What happened to him? Well, in a way, nothing. Looks to me like he's been in an accident. No, this is an experiment that took place at McGill University. Students volunteered to participate in this study of human behavior under extreme and prolonged monotony. Their hands and arms were softly covered to muffle the sense of touch. All harsh lights subdued by a mask, comfortable beds, quiet. And yet it was impossible for most of these students to take it for more than 24 to 48 hours, the psychologist Dio Heb and his associates who conducted these experiments found that deprived of ordinary everyday sensory experiences, the subjects began to lose touch with reality. Those who stuck it out began to see things, hear things. Distortions set in. hallucinations. Some began to see dots of light, lines, simple geometric patterns. Then the patterns became distorted. Another described hallucinations of little yellow men with black caps with their mouths open. One said he saw the recurring vision of eyeglasses passing in a procession like an animated movie cartoon. As the time went on, these visions became more disturbing, unreal, often frightful. Deprived of normal sensory bombardment, the brain may cease to function in the usual way. For instance, studies in France and at Harvard University have shown that hallucinations are fairly common among long-d distanceance truck drivers after long monotonous hours on the road. The cockpit of a jet aircraft droning along in the stratosphere can duplicate very closely the hypnotic monotony experienced by the students at McGill. Lack of change, little stimulation to the senses, illusion, distortion, hallucinations may set in. What happens to men in an Antarctic white out when they lose all sense of distance and all objects seem to float in midair? What is the strange exhilaration known as rapture of the deep that can cause divers to discard their breathing apparatus? These are problems that scientists in and out of the armed services are studying. This centrifuge machine, for example, helps to determine how the human senses function under abnormal conditions. Moreover, we are living in an age when man is extending his senses into farreaching realms that he once only imagined to the sources of meteors and cosmic rays. In England, a radio telescope like a huge electronic ear can catch faint radio waves broadcast from the distant galaxies and nebula of outer space. [music] Electronic senses circling the earth send information to man's waiting brain. All these magnificent tools are nothing in themselves. They are really only extensions of man's basic senses so that he can see further, hear better, feel more delicately. The simple truth is no matter how much man may extend his senses, the more he must depend upon the ones he has. And so inevitably we return to our basic theme. We exist through our senses. We are bound to reality through our senses. We learn, we survive, we grow through our senses. [music] The telephone, a symbol of man's endless search for knowledge. Invented [music] on March 10th, 1876 by Alexander Graham Bell, the first telephone scientist. Aided by Thomas A. Watson first telephone engineer working together to develop the world's first telephone. And today at Bell Telephone Laboratories, scientists and engineers [music] continue the search for knowledge which will mean many new kinds of telephone communications. Much of it is basic research, creative thinking in many fields of science including chemistry, mathematics and physics, metallergy and electronics. Bell Laboratory's fundamental research and development moving handinhand with manufacturing research and engineering performed by the Western Electric Company Bell system manufacturing and supply unit together lead to major advances in modern communications. speeding the human voice across the land by radio relay and under the oceans along the telephone cables to Europe, Alaska, and Hawaii through the development of direct distance dialing so that eventually you will be able to dial direct to any other phone in the country. Moreover, telephone research has also led to important [music] advances in national defense, in the development of the Nike guided missile, in the improvement of radar, sonar and Lauran, in the distant early warning network on guard in the far north in the bell soy to power radio signals American satellite. All these and the other developments have aided by telephone research. Research helping to shape a better world and protect it for you and your family. In laboratories, hospitals, universities, young men and women, many of them still studying for their degrees, are investigating, exploring, dedicating their minds and imaginations to the adventures of research. Studying the science of our senses, the mechanism of taste and smell. And the brain itself, the center to which the senses report, is being studied in every country of the civilized world. The final wonder is that the experience brought to our brains by the senses is recorded there for the rest of our lives. Dr. Wilder Penfield, director of the Montreal Neurological Institute, will tell us of one of the truly great physiological discoveries of the 20th century. Thank you, Dr. Baxter. [clears throat] During my life as a brain surgeon, it has been necessary to operate on good many men and women, good many hundreds, and to expose the brain under local anesthesia with the patient conscious. In those operations, it is a useful practical procedure to stimulate the cortex electrically. These are not experiments. In that process, we have stumbled quite accidentally on the fact that there is recorded in the nerve cells of the human brain. The complete record of the stream of consciousness, all those things of which a man was aware in any moment of time are recorded there. and all the sights and sounds which he ignored and the thoughts which he ignored are absent from that record. The operations are carried out under local anesthesia so that the patient is conscious and can talk. He does not feel anything when the electrode touches the brain with its gentle electrical current. It is as though the electrode touched a wire recorder or a or a strip of film and he reles a period of time. When I talk to them afterwards about how it seemed to them, they say it is much more real than any remembering. It is as though they were reexperiencing it. I believe you're about to hear the actual words of patients in response to this stimulus were quite unaware of while they were in the operating room. You will hear them as I heard them. I have a sudden feeling as though I lived through all this before. Now I see them. They're laughing, my friends. and I'm with him in a house in South Africa. They're my old friends. I hear children's voices. I hear them down along the river. I'm sitting in a railroad station in a small town. Small town in Kentucky. It's winter and the wind is blowing outside and I'm waiting for a train. I see the whole thing. A guy coming through the fence at a baseball game. I was watching these two teams play when this fella came through the fence. I hear a song. I haven't heard it since I was in high school. There it is again. The brain of man contains a record of his past, a living storehouse of remembered [music] moments of all his days. What we do, what we feel are registered there. Our multiple sensations, the whole awareness of the wonderful world in which we live. [music] [cheering] And so is recorded the total spectrum of human experience. A [music] tapestry woven from the memories of past sensations, ever growing and unique in each of us. [music] [music] [music] This has been a story of the human senses and how their signals relay to the brain of man all his knowledge. Knowledgeensible in understanding his world. How man chooses to use this knowledge and shaping his world will determine the future of mankind. Oh yeah. [music] Oh [music] yeah. [music] [music] [music] [music] Heat. Heat. [music] [music] [music] The Bell Telephone System takes pride in bringing you this program and its series of shows on science. We acknowledge our gratitude to the distinguished board of [music] adviserss covering the broad range biology and medicine, chemistry, geoysics, physics, anthropology, electronics and acoustics, mathematics, engineering. for the program you have just seen. Our thanks to the special advisers who have suggested and checked the scientific material. The Bell Telephone System is indebted to all these men and to many institutions for the generous support they've given this venture in public education through entertainment. [music]