Do letters have colors for you? Do numbers have locations in space? Do sounds have smells? If so, you might have synesthesia. And, as it turns out, you might also be more likely to have autistic traits.

Synesthesia is a tendency to automatically associate information across different senses. Commonly, people with synesthesia associate letters, words, numbers or musical notes with colors. However, there’s a diverse array of different kinds of synesthesia involving all senses, including touch, smell and taste.

For a while, psychology researchers have been interested in finding ways the brains of people with synesthesia are different. For example, there’s some evidence that synesthetes may be more intelligent on average.

Now, a new study published in in the journal Cortex by researchers from the UK suggests that people with synesthesia may also have more autistic traits. The researchers gathered together a large group of people with a range of different kinds of synesthesia.

First, the researchers surveyed the participants about the extent to which they showed signs of two kinds of autistic traits: sensory sensitivity and attention to detail. These traits are more or less what they sound like – a tendency to be sensitive to sensations (sounds or tactile sensations for example), and a tendency to focus on specific details. Both are considered core features of autism spectrum disorders.

And in the study, both were associated with synesthesia. Not only did people with synesthesia tend to score higher on both kinds of traits, but people with more types of synesthesia tended to score even higher than people with fewer types of synesthesia.

Next, the researchers had participants complete two perceptual tests. The first tested people’s ability to detect subtle changes in visual scenes. The second challenged people to find shapes embedded in larger visual scenes.

These tests involve attention to local sensory details, and people with autism tend to outperform people without autism on both. As it turned out, people with synesthesia also outperformed people without synesthesia, reinforcing the idea that people with synesthesia resemble people with autism in how they process sensory information.

The researchers are quick to emphasize that even though people with synesthesia score higher on autistic traits, most people with synesthesia don’t actually have an autism spectrum disorder. That said, the findings do suggest that people with synesthesia may be at higher risk for autism and that synesthesia and autism may have interesting neurological similarities.

Image: Flickr/Jason Brennan


  1. Luke on November 30, 2017 at 11:29 pm

    I hope you keep writing this blog for a long time, the subject matter itself is quite interesting, and you present it in a way that makes it compelling and accessible.

    • Neil Petersen on December 1, 2017 at 6:34 pm

      Thanks, Luke!

  2. Vernon Every on December 20, 2018 at 6:37 am

    Interesting! For the record, for me John and north are red, Peter and east are green, Timothy and south are yellow, Paul is orange, Mary and west are blue and I could go on with other names but not much in the way of further colours.

    • Neil Petersen on December 20, 2018 at 2:19 pm

      Cool! I don’t have a citation on this, but I believe I read that the letter A is red for a disproportional number of synesthetes. It seems like John and north could be the letter As of names and directions respectively. 😛

  3. Roberta on March 15, 2019 at 3:31 pm

    My synesthesia connection is with numbers and colors. Have you found a trend at all that associates specific numbers and colors? For example: 3 and yellow, 4 and red, 5 and blue?

    • Neil Petersen on March 17, 2019 at 11:49 pm

      Generally, people with synesthesia have different associations, but there are some associations that tend to be more common. For example, I believe ‘A’ is often (but not always) associated with red. As far as colors and numbers, I’m not sure about that one. It’s an interesting question, I should probably do a post on it!

  4. Liz on July 12, 2019 at 12:44 pm

    I find I associate numbers and colors with feelings. Numbers or colors that I see as sad nervous or angry will make me extremely uncomfortable, and start to feel that feeling. Is this part of synesthesia? I also have many “autistic” traits ( but do not have autism.) My daughter does have autism and also associates feelings with numbers and colors.

    • Neil Petersen on July 12, 2019 at 4:46 pm

      That’s interesting! You might want to look into ordinal linguistic personification, where people associate numbers or letters with personalities.

      This paper cites a few case studies that are similar to but not exactly the same as what you’re describing: 1) someone who has emotions triggered in response to textures 2) someone who sees colors in response to pleasant or unpleasant images 3) someone with Asperger’s who understands emotions better when they’re associated with colors.

      My personal, non-expert impression is that what you’re describing does seem related to synesthesia, but that it’s not in an area that’s been well-enough researched to say exactly what it is. For that matter, researchers still don’t have clear answers on what synesthesia is, and what exactly is and isn’t synesthesia!