Could reading an ordinary road sign become this colourful? (Image: Stockbyte/Getty)

Brain training for synaesthesia – the condition where you mix up sensory information – doesn’t yet exist, but it may be just around the corner. For the first time, people have been taught to experience a common form of synaesthesia, where letters appear as certain colours, in their everyday life.

By the end of the nine-week course, most of the volunteers had the bizarre experience of seeing text in the real world, on road signs, for instance, take on certain hues. “The colour immediately pops into my head,” said a subject who experienced some of the strongest effects. “When I look at a sign the whole word appears according to the training colours.”

Synaesthesia is a rare condition that runs in families. It has traditionally been attributed to people’s brains developing in such a way that their sensory signals get mixed up. So “Tuesday” might always evoke the colour pink, for example, or the word “tree” might taste like popcorn.


More recent research has also implicated early life experiences. For instance, some people with letter-colour synaesthesia have reported that their pairings match the colours of a childhood alphabet puzzle or fridge magnets.

Out of the lab

So if synaesthesia can be learned early on, how about in adulthood? Two years ago a group based in Amsterdam found they could induce some aspects of synaesthesia by getting people to read books where some of the letters appeared in certain colours. This improved their scores on the Stroop test, a task where they had to name letters presented in different colours. However, their synesthetic abilities stayed in the lab – they didn’t see coloured letters in real life.

A group led by Daniel Bor at the University of Sussex in Brighton, UK, wanted to find out what more intensive training could do. As well as using specially coloured e-books, they gave people daily half-hour training sessions to teach them 13 letter-colour associations, using progressively harder tasks (see “Teach yourself synaesthesia,” below).

As well as passing several lab tests of synaesthesia, nine of the 14 volunteers reported that they saw coloured letters when they read ordinary black text, to varying extents. Many of the participants were seeing strong effects by week 5, and some were seeing coloured letters appear on a daily basis. “They were excited to have these extra experiences,” says Bor.

Unfortunately, their newfound prowess faded after training stopped. Three months later, all the volunteers had lost their synaesthesia – probably because of all the black text they read in everyday life, Bor thinks – although they still scored higher on the Stroop test than they had initially. Bor plans to repeat the work with adults learning a new language with a different alphabet, such as Hebrew: if they only ever read the language in modified form they shouldn’t experience such detraining, he reasons.

IQ leap?

“It’s a very encouraging result,” says Olympia Colizoli of the University of Amsterdam, who was involved in the first study that managed to induce synaesthesia in the lab.

Bor says the results support the role of learning in synaesthesia. He thinks young children with the right genetic predisposition might unconsciously use colours as “hooks” to help them with the tricky task of learning the alphabet.

Learning to become a synaesthete might have an unexpected benefit. The volunteers in the study gained a whopping 12 points in IQ tests, unlike a control group who had no training. Bor says, however, that this might be a general benefit of the intensive training with memory-related tasks, rather than the synaesthesia training per se. “But it’s very rare to report such a large IQ jump so our suspicion is it’s something to do with synaesthesia,” he says, adding that he may in future make the training tools available online.

Colizoli points out that people with spontaneous synaesthesia also have better memories for information relating to their mixed-up senses. She agrees with Bor, however, that the IQ jump could be due to a general training effect.

Journal reference: Scientific Reports, DOI: 10.1038/srep07089

Teach yourself synaesthesia If the latest research gets translated into an online learning tool, your training might look something like this: Training Half an hour, five days a week, on progressively harder tasks that test your recall of colours associated with 13 letters of the alphabet Homework Read e-books where those 13 letters always appear in the right colours Reward yourself In the study, people got small sums of cash if they scored higher than the previous week, which may have helped motivation Let the weirdness begin By the end, most of the volunteers were starting to see ordinary text in real life take on the learned colours Keep at it In the study the effects faded after training finished. It is not known how much effort is needed to maintain the effect but regular training should help