Most people are familiar with the five senses: touch, smell, taste, sight, and hearing. But did you know that all five of your senses work together rather than separately? All five senses collaborate to feed information about our surrounding environment into the brain, a concept known as perception. Perception is vital to human survival, as our senses help us do things like detect threats, locate food, and communicate with other humans. While our senses are connected, each of the five performs a vital function.
One of the most important senses for human survival is touch. Touch is primarily a function of the skin. Skin cells send signals through the nerves to the brain, where these signals are interpreted. Touch allows us to judge how soft or firm an object is, differentiate shapes and textures, and experience the sensations of temperature and pain. Being able to feel the texture of a potential food source has helped humans from an evolutionary perspective, as a finer-tuned sense of touch made it easier to identify poisonous or spoiled foods. The ability to sense temperature and pain are also vital to survival; being able to feel if an environment is too hot or cold motivates a person to seek shelter from inhospitable conditions, and pain is an important signal to the brain that something is harming the body and needs to be avoided. Touch also has a social component. As social creatures, humans seek to form meaningful relationships and have positive interactions with other people in order to survive as a group. In fact, social touching is so important that studies have revealed that babies who are not touched enough by caregivers in infancy can suffer severe emotional, developmental, or physical consequences, potentially even death.
Smell is an often-overlooked sense but is very important. The olfactory system allows the nose to take in smells and even locate them depending on which nostril the smell enters. The primary biological importance of smell is its role in identifying edible foods. Smell and taste work more closely together than any other senses, and we are more likely to enjoy foods that we perceive to have a pleasant aroma. Unpleasant smells, from an evolutionary perspective, help humans avoid consuming inedible or rotten foods. Everyone knows how easy it is to tell if milk has spoiled: Just give it a good whiff! Many studies have shown that smell also has a powerful effect on memory. Psychologists have suggested that a particular smell associated with a time and/or place can stimulate a person's ability to recall a memory as much as or more than a visual cue. Another function of smell comes into play when people assess the attractiveness of a potential partner. Both "regular" smells and the subconscious smell of pheromones can influence a person's perception of another's physical appearance. In one study, the same female volunteer was assessed by male suitors while wearing different types of perfume. When the men found the perfume she was wearing pleasant, they perceived her to be more attractive and guessed her weight as lower than when her scent was perceived as less pleasant and when she was not wearing any perfume at all.
Closely linked with smell is the sense of taste. Taste's importance to human biology is perhaps the most obvious of all of the senses: it plays a key role in food selection. Our ability to perceive the taste of certain chemical compounds as unpleasant can save us from ingesting food that is poisonous to humans. Studies have even suggested that an individual's personal taste preferences may be linked to specific bodily needs and aversion to foods that have previously made that person sick. We taste through the taste buds located on the small bumps, or papillae, of our tongues. Taste buds distinguish five distinct types of flavors: sweet, salty, sour, bitter, and umami (savory, "meaty" flavors). Each has a dietary function: sweet flavors usually indicate nutrient-rich foods like fruits and vegetables, salt allows for the regulation of electrolytes, sour flavors indicate the presence of essential acids, bitter flavors help the body detect toxins and inedible substances (in most cases), and umami allows the body to identify food sources rich in amino acids, proteins, and glutamates.
If any one sense could be considered the most important, it might be sight. Sight is considered the "dominant" sense; that is, it is the sense that the brain relies on the most for input of essential information. Without the ability to see, the brain cannot easily navigate its environment, identify threats, locate food sources, or identify people for the purpose of communication. Those with vision impairments need assistance to compensate, and it is important to take care of one's eyes by getting proper nutrition and avoiding sun damage. Vision is tied to mobility and can affect the body's ability to balance and awareness of the body's spatial relationship to objects. Vision is also an important factor in memory.
Vision and hearing function together in many cases, with visual input affecting how the ear perceives sound. The most essential function of hearing is our ability to communicate with others. Without the ability to effectively communicate with other people in order to cooperate and pool resources, the human species would not have been so successful. Having good hearing is essential for the acquisition of language skills in young children, and studies suggest that an impairment in hearing can seriously affect a child's ability to learn in general. Hearing is such a powerful sense that it is often used as the most important substitute for vision in the blind. Many animals, and even some humans, can navigate their surroundings using echolocation, or the ability to detect the echoes of sound waves bouncing off of objects. Even on a more basic level, the ability to hear one's surroundings is important for orientation of the body within its environment and the detection of potential hazards.
How They Are All Connected
Lots of new studies are being done every day on the connections between the senses. While all of our senses have an important function independently, they also build off of one another to influence overall perception. In addition, some people even have a condition known as synesthesia, in which the senses combine their information in peculiar ways, resulting in the ability to hear colors or see tastes, for example. But even without synesthesia, all of us experience some degree of overlap between the senses. For example, sight and hearing are closely tied, as seen in a phenomenon called the McGurk effect: If you hear a person pronounce the sound "bah" but it appears as though their mouth is pronouncing the sound "fah," your brain will hear the sound "fah," even if that is not the sound it is actually hearing. Hearing and vision also work together to help the body orient itself within the environment, and the two senses being out of sync can result in difficulty with balance and spatial reasoning. Smell and taste provide another well-known example of senses working together: The presence of a strong, unpleasant odor will influence how the body perceives the taste of an otherwise pleasant food. Even physically, the throat connects the nose and mouth, and it is impossible to completely disconnect the senses of smell and taste. Other connections between senses are less understood, but scientists are learning more and more about perception and the way our senses work together.