Few have a rare disorder that turns our senses around as these individuals experience something few ever do, and we question their sanity.

Psychedelic substances aren't the only things that can change our perceptions and distort our senses in ways we never dreamed of. No one would ever expect to be able to taste a scent or hear a color, but that is exactly what people with a rare form of sensual aberration, known as synesthesia, experience. For some, it may lead to innumerable appointments with mental health professionals who cannot see that it is not a mental illness but a possible change in brain neural integration, and it can be a significant benefit to some.

I recall having a young man who had recently taken a tab of LSD tell me, "I just inhaled the universe." Of course, a comment like that in a different setting would have resulted in immediate hospitalization, evaluation, according to usual, simplistic means, and, most probably, treatment with antipsychotic medications.

But we know some can change perception and use it meaningfully to promote creativity and even lead to an extraordinary career. One such case in point is Christine Nagel, the master perfumer at the incredibly expensive fashion house of Hermès, who “sees” and “feels” scents. But does she truly have synesthesia, or is she what is known in the perfume business as a "nose" able to detect various subtle scents within a perfume?

A perfumer or aromatherapist who can evoke specific feelings or ideas through their work is called a nose. Distinct aromas have a heightened impact on them.

Women's scarves and shawls at this company can cost several hundred dollars; while perfumes are not as expensive, they are not inexpensive. The master perfumer, therefore, has a great responsibility and can use her extraordinary ability to her benefit. This master perfumer says that she can feel her perfume scents.

How common is this unusual ability? Two to four percent of the population experiences synesthesia, in which stimuli experienced in one sense can simultaneously trigger feelings in other senses. Although synesthesia can theoretically involve any two senses, most studies have concentrated on the two most prevalent types, where auditory tones and achromatic (colorless) numbers create highly noticeable and vibrant colors. And this ability, although seeming to be more of an annoyance than anything else, has been found to have advantages for those who possess it.

There was considerable improvement in both recall and recognition memory ability for color stimuli in grapheme-color synesthetes in one study. Possible interpretations of their findings include stronger memory traces in episodic memory, improved retrieval strength, and more efficient and controlled encoding of color stimuli. If this ability can be a potent effect for memory, it is then, indeed, a beneficial brain change. The question, then, is whether people can train themselves to use this potentially inert ability to their advantage.

Training Synesthesia Efforts

A study found that half of people who do not have synesthesia can experience perceptions similar to synesthesia after around five minutes of visual deprivation. These findings cast doubt on certain parts of the cross-activation hypothesis. This hypothesis asserts that synesthesia develops when normally different regions of the brain experience an increase in neural connections with one another. Is it neural connections or a manipulation of some sort?

Involuntary mixed sensory experiences are the result of this overconnectivity, which enables activation in one area of the brain to directly affect another. The overconnection idea would mean it has a developmental component that is beyond the reach of anyone who doesn't have this ability. And the study provides more evidence that synesthesia is a universal trait that a disruption in the normal regulation of sensory input can trigger. So it would seem, the needed connections might be there, but not producing until some activation prompts them to do so.

There have always been these two models of synesthesia: the neural connection model and the other of manipulating sense material. Studies have shown that the manipulation model works and requires only minutes to establish in naïve subjects. Therefore, this strengthens the idea that everyone has this ability, but they have not been taught to use it. If someone teaches them, it might significantly affect their memory in various aspects.

While promoting synesthesia in ourselves as a memory manipulation device is intriguing, researchers are not convinced that the two types of synesthesia (neurodevelopmental and learned) may be the same. Even in those who rarely have synaesthesia, intensive training of letter-color connections can change their conscious perceptual experiences, leading to phenomenology similar to synaesthesia. But does this training begin a brain series that results in actual physical change? Research in this area has not been initiated at this point.