We have more than five senses; Seeing, feeling, smelling, tasting and hearing are taken for granted by most people – but not by scientists. Recent discoveries suggest we may have abilities we never imagined. (Published 1964) (2023)

People tend to take their five basic senses for granted. As long as nothing goes wrong with any of these senses, the average person continues to see and touch, smell smells, taste tastes and hear sounds without giving a second thought to the industrious and sensitive skills that keep them so well informed about the complex world . around him.

Fortunately, scientists did not share this general indifference. In fact, information about the senses has been of the greatest interest to scholars since Aristotle, and as such information touched on fundamental philosophical problems related to the nature of reality and the perennial question of how do we know what we know and whether we really know. . Over the past 100 years, research into the human and animal senses has produced a body of information that is extraordinary in quantity and nature.

One of the most surprising observations was one of the most recent: the great possibility that some people can see with their fingertips. The first news of this strange phenomenon came from a Russian scientist early last year. He reported the case of a 22-year-old girl who could identify colors by touch and read the text of a newspaper by running her fingers over the print.

Our own scientists greeted the news with skepticism. But those first impressions soon turned into shock with the revelation that an American psychologist, Dr. Richard P. Youtz of Barnard College, tested an American woman who could recognize color by touch alone. Meanwhile, the Russians claim they've discovered two more cases of fingertip vision and are having their top scientists review previous findings. There seems to be strong evidence that certain people may possess this "sixth" sense.

Such a discovery draws new attention to what science knows about the senses. How strong are they? what are your limits Can a sense be trained beyond its "natural" limits? Do we have any other hidden senses? Indeed, to begin with, what is meaning?

A sense can be defined as a mechanism in the body that enables a human or animal to receive specific information about the world and transmit it to the brain via neural pathways. Each sense has its own specialized cells to gather its own type of information: sounds, tastes, images, etc. And each sense has its own area of ​​the brain that monitors the information it receives.

The data collected and processed for us by the senses are of a physical or chemical nature. For example, the ears and eyes are physically stimulated by sound or light waves. Taste and smell are produced through chemical contact with the taste buds, or olfactory centers.

Every sense has what science calls its "specific disposition." This means, for example, that our sense of sight is usually not awakened by a loud noise and our sense of hearing is not awakened by touch. Our eyes can only see, not hear. This is why when you get a punch in the eye, you "see stars". The sense of sight responds to the stimulus in the only possible way, by seeing.

Being able to 'see' with your fingertips may mean that a valuable exception to the 'specific deployment' principle has been found. Ashouldbeing able to receive stimuli such as heat, cold, touch and the like through the fingertips only. The Barnard-Russian findings have sparked much speculation by scholars as to whether, if the reports are true, the new sense is a sense in the true meaning of the word. Several theories have been proposed that attempt to solve the "specific purpose" dilemma; These range from suggestions that the "seeing" fingertips have some kind of retina, to the belief that the subjects must be telepathic in some way. (The latter possibility was heralded by a Russian; very few, if any, top American scientists in the field of sensory research now take extrasensory perception very seriously.)

Another feature of the senses is the tendency of entire species, from insects to humans, to operate on different "spectra" or "channels" for each sense. The simplest example of this is hearing. A human cannot hear the monitor scream from one mouse to another when the cat approaches; A human's ears do not have the same sound frequency level as a mouse's. The sea is filled with the sounds of fish calls, courtship calls and warning calls, but we can hear very few of them. There are similar "spectra" for other senses. for taste, smell. see and even touch. Of course, there is much overlap in the "spectra" of meaning. A cat can hear its master's voice as well as the mouse's cry.

In general, the fact that higher frequencies cannot be heard by the human ear is a blessing. If that were the case, humanity would be constantly listening to a cacophony of background noise that would be maddening. It's also a blessing that our other senses have limitations, otherwise we'd pick up smells well left to the dog or scavenger, or see things after dark not suited to humans but to animals.

A clear fact that scientists have established is that the human senses, measured by our own sensory "spectra". high compared to the senses of animals, a fact that may surprise those who think of humanity as some kind of second-rate physical achievement.

Human vision, for example, is possibly the most versatile in nature. People with normal vision can see a grapefruit 1,250 feet away, just inches from their nose. A hawk's distance vision is better than ours in daylight, but its eyes don't reach as far as ours when the sun goes down. A bee can see more than we can see up close, but its distance vision is terrible compared to that of a human. We can perceive distant objects 100 times smaller than what a bee can perceive.

Our ability to perceive color is undoubtedly one of the best in the animal kingdom. Ostriches can distinguish between colors and even fish can distinguish all the colors of the rainbow. But . The human eye could theoretically distinguish hundreds of thousands of variations in hues, too many variations to have individual names, and no other animal can match it with a spectroscope.

SOME creatures hunt during the day but are completely blind at night and therefore hide in the twilight. Another group cannot see well during the day. and they hunt at night. The highly adaptable human eye can function perfectly during the day and comparatively well at night. Our eyes have a billion to one visual intensity range; That is, we can see, at least partially, in the glare of a tropical sun or in the faintest light of stars.

Hearing in humans is also a powerful sense; Within the acoustic "band" that the human ear is designed for (roughly 20 to 20,000 vibrations per second), it is as sensitive as any in the animal kingdom. A dog's ears rank highly among vertebrates, but on our own "spectrum," ours are just as good. Our hearing also includes a sense of direction and the ability to tell where sounds are coming from. This ability is extremely acute, and tests have shown that we can learn, for example, to pinpoint the precise location of 18 different instruments in an orchestra at 50 feet with their backs to the orchestra.

On its own, taste is perhaps the most limited of all our senses; We have about 10,000 taste bud receptors. or specialized taste cells on our tongue that can only distinguish between four tastes: sweet, sour, salty, and bitter. But fortunately this dull sense is not required to function on its own. This is where our sense of smell comes in, which, like our sense of taste, only needs 1/25,000 of the molecules to alert you and is infinitely more diverse.

Sherlock Holmes believed that a good detective should be able to identify 75 different smells. But he underestimated humanity. The fact is, the 600,000 cells connected to the nose's olfactory center can perceive seemingly unlimited smells. The human nose has its own olfactory spectrum in which to work, just as the ear and eye have their spectrums of sound and light waves. We couldn't smell each other like bees to a flower, but we're fine in our own area. For example, a recent survey counted 17,000 smells that the human nose can distinguish between.

In terms of distance, we're nowhere near the smell world record. It is held by the male silkworm moth, which can spot its mate from seven miles upwind. But that same moth is smell-blind compared to us when it comes to sizzling steak or lamb stew.

The human sense of touch requires up to 10 billion times more energy before we can feel an object than sight before we can see an object. Even so, touch could hardly be called a weak sense. Just 1/1,000 of an ounce of pressure on a hair on an arm or leg is enough to alert us. And without any training, your fingertips can distinguish between smooth glass and glass with an etched pattern no deeper than 1/2500th of an inch. Our sense of touch also allows us to tell the difference between hard and soft, wet and dry in fractions of a second. slippery and sticky, and to distinguish between the different textures and other qualities of a large number of surfaces.

Aristotle was the first to point out the "Big Five" among the senses: touch, hearing. see, smell and taste. A few more have been discovered in recent years, including a special sense of direction and balance, a sensory organ in the brain itself that regulates body temperature, and another that regulates blood carbon dioxide levels. We also have a sense that allows us to distinguish weights with great precision. More recently, scientists have also discovered "residual" senses, or latent sensory abilities, that some people can develop.

Barnard-Russian's fingertip discoveries fall into this category. There is evidence that the subjects may have improved their strange abilities with practice. If true, does this mean that a human being can expand the outer limits of his sense organs? The answer is no. A person with, say, 20-20 vision cannot expand the range of their vision; the built-in limit is absolute. We also have such limits when it comes to hearing, smelling, touching and tasting.

However, certain sensory organs can be trained to bring out hidden qualities or to reach their "true" limits. Blind people, for example, can often learn to “hear” their location. To do this, they use a sense that most people have to some degree but rarely need to use; This is the innate ability to pick up tiny echoes reflected off nearby objects. A blind man tapping his cane sends out some kind of signal and picks up its echoes on furniture and walls. Blind people often click as they walk, subconsciously sending out sound signals to help them find their way, just like bats.

This latent human sense is, of course, weak, but with patient training one can reach its ultimate limit. So far it has been found that a human can learn to echolocate a six inch diameter rod at least three feet away.

The ability of blind people to determine their direction and position once led scientists to believe that certain people might have some form of "face vision." The discovery of the existence of the subliminal "echo sense" seemed to put an end to such speculation. However, it is now being suggested that blind people can take advantage of both this "sense of echo" and our skin's slight sensitivity to light.

It has been clearly established that some people's fingertips can be trained to "hear". dr R.H. Gault of Northwestern University proved it 35 years ago. He built a device that allowed the highly amplified human voice to come into contact with a subject's fingers. A training period enabled a subject to recognize short phrases vibrated against their fingers three times out of four.

The fact that our senses of taste and smell can be trained to peak proficiency is evidenced by the fact that major food and beverage industries spend millions of dollars hiring and training specialist tasters for their products. The sense of taste of such a specialist becomes extraordinarily sensitive. He soon learns to recognize the chemical content of almost anything he puts in his mouth. Standing blindfolded in a room full of people, a trained nose can tell who is using which powder or hair tonic, or if someone has taken a vitamin pill in the last 24 hours.

It is said that Helen Keller was able to determine the identities of her friends based on their individual scents. It wasn't because he had developed a sense of smell that was basically superhuman or a bloodhound's vanity. She had simply taught herself to notice the perfumes, hair oils, and other olfactory cues that her friends identified.

We can also be trained to the extreme limits of our sense of touch. Large textile houses have professional "texture sensors" that can identify countless fabrics with a simple touch. These "sensors" become so fantastically dexterous that even when collodion is applied to their fingertips, some can still distinguish dozens of substances by touch alone. And some can just bang a piece of cloth with a stick and tell everything they need to know about it.

Although the senses can be trained to reach their outer limits of acuity, those limits cannot be reached with drugs like mescaline, L.S.D. or peyote, despite popular belief to the contrary. Drugs of this type give the user strange and often fascinating experiences; and there are many accounts of people who have gained insight into themselves and the world under the influence of such drugs.

However, the main effect of these drugs is probably not on the senses as such, but on the brain. One can experience feelings of heightened acuity, but these are subjective. Drugs have a profound effect on what the mind itself does with the images and sounds one perceives, but they don't really allow one to see or hear at a greater distance, or otherwise expand one's innate sensory limitations.

IF the Barnard-Russia experiments prove that humanity has some sense of sight, it could have very practical applications. If means can be devised to enhance this weak ability, the blind could use them to read the ordinary printed page, and a whole new aesthetic synthesis of the visual and the tactile can take place.

Such a utilitarian use of our growing sense knowledge already has a long tradition. When a new fact is discovered, it is often followed by practical suggestions as to how it might be used, or inventions based on it.

For example:

Humans are not particularly sensitive to magnetic phenomena, but certain other life forms have been discovered to be. Salmon and trout react aversely to pulsating electromagnetic fields in the water. The discovery of this special sense now allows fish and game inspectors to herd their salmon and trout into special pens as the fish migrate upstream, simply by turning a stretch of river into an electromagnetic field.

EVEN unicellular paramecium has a seemingly useless magnetic sense: it always swims towards the negative pole when the positive and negative conductors are submerged in water. An extension of this sensitivity is observed in men and women who produce sperm; the male-producing sperm moves to one electric pole, the female-producing sperm to the other. This ability is used in a device to control the sex of herds and herds in artificial insemination.

Many other possibilities arise from the new information about the senses. A new multi-channel radio transmitter has been proposed, based on humanity's ability to filter out the voice we "want to hear from a cacophony of others." Based on new data suggesting that mosquitoes are attracted to people with a slightly warmer skin surface, a mosquito repellent based on a reduction in skin temperature has been proposed. Research on minnows has proposed a shark repellent, which has found that when a minnow is injured, its skin oozes a secretion that warns its fishy brother to stay away. If sharks have the same ability to smell a warning from a wounded brother, a truly effective shark repellent can be found:

SOME inventions are made by studying the special properties of animals and insects. One is an aircraft speedometer based on the bee's strange compound eye, which allows it to calculate its movement over the ground. Until the invention of this device, pilots could only measure their speed in relation to wind speed. So if a plane was flying at 100 mph into a 100 mph headwind, the pilot had no instruments to tell him he was getting nowhere. With his ground speed gauge, he now has wings as confident as a bee, or almost so.

These are just some of the facts that have been discovered about the senses in the last century. The scope of this knowledge and its practical applications seem almost unlimited today.

One thing is clear. We should not take our senses for granted. Recent experiments have shown that the senses are not only important, but essential to the survival of the human mind. In these experiments, subjects were deprived of any possible sensory stimulation; their eyes were covered with goggles, their hands were covered so they could not feel; They were isolated from contact and could only hear a constant humming in the background.

In the environment, the subjects soon stopped thinking together. Some had hallucinations, some erupted in irrational rages, some had delusions that they had two bodies or that their minds were separate from them and were wandering in space. None was unaffected.

The classical view has always been that "the mind" is something that can exist other than the senses. But now it seems that higher brain functions are vitally dependent on the senses, that without our senses we would become mindless in no time. It is fortunate that scientists have kept their eyes and ears on our eyes and ears. and fingertips too.