Take artist Concetta Antico, for example. She’s one of a few individuals confirmed to have tetrachromacy – a condition caused by a gene that alters how a person’s retinas develop. The average human possesses three types of cone-shaped cells that determine color perception. Concetta, however, was confirmed by genetic tests to have a fourth type, giving her the ability to see a much wider spectrum of colors than average.
Instead of having intensified vision or smell, some people perceive unique combinations of the senses. The phenomenon known as synesthesia can cause different senses to overlap. Individuals with various types of synesthesia report being able to taste words or to see the colors of musical notes. Some people experience multiple forms of synesthesia at once, although researchers are still uncertain of exactly how unusual the condition is and what causes it. One theory suggests that synesthetes may be equipped with extra neural connections that lead to a collapse of boundaries between senses over time.
Characters with extreme senses fill the pages of comic books and science fiction novels, but there are a number of real disorders that can cause heightened sensitivity to certain stimuli. Sometimes, such as in the case of sensory processing disorder, it can become a burden by causing the body to over-respond to everyday sensations of touch. Others, like hyperosmia, intensify odors and occasionally taste. The rare condition of hyperacusis amplifies an individual’s auditory perception, making noises of a certain frequency seem unbearably loud.