The Science Behind Synesthesia: People Experience More Sensitive Sensory Connections Between Words And Shapes

An estimated one to four percent of people in the world have the trait for synesthesia — an involuntary joining of two different senses. These individuals, known as synesthetes, will hear color and see sounds.

A new study from neuroscientists at Emory University has found that people who experience synesthesia are also more sensitive to associations between the sounds of words and visual shapes than other people, according to a news release on Science Daily. 

Synesthesia Scientists are still looking at how synesthesia affects the brain. Photo courtesy of Pixabay

"There's been a debate about synesthesia," said lead researcher Krish Sathian in the release. "Are the associations synesthetes have just extreme versions of cross-modal correspondences that other people have, or are they qualitatively different?"

Sathian and his team of researchers found that people with synesthesia were more sensitive to other sensory associations as well. In synesthetes, there was a correspondence between the sounds of pseudowords — words without meaning in English — and how rounded or angular a shape was.

"It shows that something about their synesthesia is spilling over into another domain," he says. "But that spillover is limited to a correspondence that is post-perceptual and symbolic — it's not purely sensory."

These correspondences are called "sound-symbolic," and may be relevant to the evolutionary origins of language, Sathian added.

The team of researchers worked alongside 17 people with synesthesia  and asked them to take a form of the implicit association test (IAT). The IAT works by assessing "cross-modal correspondences," for example, musical notes described as being "high" or "low.”

Previous brain imaging studies have also proved that people with synesthesia tend to have brains that are wired differently, and we still have many questions about the condition and how it works. Scientists have proposed that synesthesia represents alterations in pruning, which is the process of editing connections between brain cells.

Source: Lacey S, Martinez McCormick M, Sathian K. Synesthesia Strengthens Sound-Symbolic Cross-Modal Correspondences. European Journal of Neuroscience , 2016

Read more:

What It's Like To Experience Synesthesia: The Taste Of Music And Colors Of Language

Inside Synesthesia: Closer Connections Between Brain Regions May Cause Senses To Blend

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