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Synesthesia is a condition where presentation of one perceptual class consistently evokes additional experiences in different perceptual categories. Synesthesia is widely considered a congenital condition, although an alternative view is that it is underpinned by repeated exposure to combined perceptual features at key developmental stages.

When I first heard about synesthesia, I thought it was a little hokey. But when I discovered it was real, I was fascinated – perhaps because I don’t seem to have much sensitivity in my individual senses. To have them multiply active – well – I am jealous.

It is a rare condition, but the science is pretty simple. Cross talk between areas of the sensory cortex causes electrical activity in one area to flow into another area and two senses get activated by a single sensory dimension. If you are not familiar with what this feels like, imagine hearing a C-flat and experiencing both the sound of the C-Flat and the color olive green. Synesthetes describe this as hearing a color or tasting a sound. Like I said, pretty cool.

With this in mind, consider the findings of this paper in Nature. I always thought that synesthesia was a genetic condition, but it seems that there are two theories: genetic and early stage (very young children) associative learning. Perhaps the cross-talk is genetically wired from birth, but it can also be generated if a young child, whose brain is still wiring itself, frequently experiences a stimulus that has a consistent pairing of two sensory dimensions.

The researchers in this study wondered. If synesthesia could be generated through associative learning at a young age, perhaps really intensive training at an older age could do it too. So they tried it. This study found evidence that it can. They even followed up to see if the synesthetic experience transferred outside of the lab after a delay of three months. Much of it had faded, but some of the experience remained. So perhaps more than the 9-week training would sustain it at a higher level. Perhaps we can use an app such as we discussed here.

Image Credit: Drew Coffman

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