Here's the test scientists use to tell if you have synesthesia

Erin Brodwin
Mar 13, 2015, 7:47 AM

Wherever I see the colour ‘4,’ it glows orange in my mind’s eye.

I still see it as black on a white page but I know, somewhere deep down, that it’s really orange. It’s the same way I know that 7 is dark purple or 8 is royal blue.

While synesthesia remains largely a mystery to scientists, a new study published March 4 offers a glimpse into what’s going on in the brains of those of us who have it. The researchers used a test, which we discovered is also available for free online, to evaluate a sample of random people.

A typical question on the test consists of looking at a number, letter, or month, and selecting the colour it matches with.

It looks like this: To confirm you’re not just making it up, the test has you match each number and letter with its colour 3 times, in random order. Most synesthetes are have a very particular colour that they associate with each letter or number, right down to the exact shade and brightness. The tool lets you get pretty specific.

Then, you’re shown a number or letter (in a random colour) for a brief moment — and then asked to identify if it was the right colour.

Here’s what a typical synesthete’s test results look like. A colour is backgrounded in black (like the letter C below) if the person taking the test didn’t associate it with a colour: A score below 1.0 is ranked as synesthetic, because it means you consistently matched each letter with a specific colour. In other words, your choices weren’t random. The precise colour you picked each time is shown in each box along the row. The closer the match for a particular letter or colour each time, the smaller the bar immediately to the right of that row.

By comparison, the test results of a non-synesthetic person might look like this: Nearly each of the letters or numbers in each square are different colours, and as a result the bar to the right of each row is long. In other words, a non-synesthete is picking a colour at random.

It sounds like a silly test, but there are so many numbers, letters, and colour choices that even when non-synesthetes are asked to take the test using memory (meaning they’re trying to fool it), they usually only score around 2.0.
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