Become a synesthete in five minutes or less

A recent study shows how our senses can team up to paint a picture of our surroundings -- no brain rewiring required.

Are you looking to discover whether you are a master of the senses? If you have a specific answer for what the color blue might taste like, or a high note on a violin smells like, you just might be a synesthete. Synesthetes, or individuals with synesthesia, often have cross-sensory experiences where activating one of the five senses can activate another at the exact same time. One way to see if you are a synesthete is to take the online Synesthesia Battery, validated by Carmichael et al in 2015 as an effective identifier of grapheme-color (letter to color) synesthetes. But even if the battery results don’t go your way, you might be in luck: the brain connections required for synesthesia might already be lying dormant in your brain, just waiting for the right sensory experience to wake them up.

There are two main theories to explain how synesthesia works in the brain. One of them, the cross-activation theory, proposes that synesthesia develops over a time period of months or even years. In that time, brain connectivity increases dramatically in sensory regions that are paired together in synesthesia. By the rules of this model, non-synesthetes don’t have the connectivity necessary for synesthetic experiences to happen in a flash – it should take years.

If you can use sensory teamwork in a dark room to figure out your surroundings in a matter of seconds, who’s to say taking away one sense from a person—light, for example—couldn’t evoke a synesthetic experience purely based on what someone infers that they see?

In contrast, the disinhibited feedback model of synesthesia states that anyone could potentially become a synesthete, because our senses work together all the time. Here’s an example: if you are in a dark room and hear footsteps approaching from behind you, you can assume that someone is nearby. In that moment, even though you don’t actually see the person sneaking up on you, the brain’s activity in the visual cortex increases—because you’re using the power of sound to tell you what you see. If you can use sensory teamwork in a dark room to figure out your surroundings in a matter of seconds, who’s to say taking away one sense from a person—light, for example—couldn’t evoke a synesthetic experience purely based on what someone infers that they see?

Anupama Nair and David Brang recruited undergraduate students from the University of Michigan to put this question to the test. They placed the students in a dark environment, telling them to keep their eyes closed. After the students had acclimated to the dark, Nair and Brang had them complete a visual imagery task where they paired letters in the alphabet with certain characteristics—for example, answering “yes” or “no” to whether the letter A has any curves in it. This task was meant to keep the students occupied while Nair and Brang could try to trigger synesthetic experiences in the background.

While the visual imagery test was going on in the foreground, something slightly different was happening behind the curtain. At the very beginning of the experiment, Nair and Brang told the students that they might experience visual sensations or experiences during the testing, even though their eyes were closed. If they did, the students were instructed to press a button. As the students were tested on their alphabet soup, beeps would play at random from two locations in the dark room. The researchers hoped for a response similar to the sneaking-up example: depriving the subjects’ visual sense would encourage their sense of sound to make connections with the visual cortex when the beeping began. The new sensory connection between the sound and visual systems would produce a visual perception like a bright color. If observed, these results would mean that college students without synesthesia could display synesthetic symptoms—a bright color in response to a beeping sound—in only five minutes, providing support for the disinhibited feedback model.

The brain machinery for synesthesia might already be in our brains: it just needs the right gains and losses of senses to make new connections and cause sensory experiences.

Nair and Brang’s results supported their predictions: the beeping induced visual perceptions in 57.1% of the non-synesthetic students. Students in a dark room heard a sound, and their brains made sensory connections and inferences to explain the phenomena, producing a visual image just like in individuals with synesthesia in just five minutes. Nair and Brang’s findings add some street cred to the disinhibited feedback model of synesthesia, hinting that the brain machinery for synesthesia might already be in our brains: it just needs the right gains and losses of senses to make new connections and cause sensory experiences. There’s still more research to be done, but the results present new information on how multi-sense experiences relate to synesthesia, and what exactly happens in the brain when two senses decide to work together.