'How sour sweet music is…'

"How sour sweet music is…" Shakespeare wrote in his play Richard II "…when time is broke and no proportion kept!". The musician known to researchers as E.S. can probably sympathise with this quote more than most – she consistently experiences specific tastes, like salt or bitterness, when she hears certain pairs of musical tones. This cross-talk between the senses is called synaesthesia, although it is a rare form. Most synaesthetes experience different colours when they hear sounds or see certain numbers/ words.

Doubters have suggested people with synaesthesia are making it up, or that they have a vivid imagination. But scientists at the University of Zurich tested E.S. on a version of the Stroop task and found evidence that what E.S reports is real. E.S. was able to identify musical tone-intervals faster than five control musicians when researchers applied to her tongue the taste that she normally experiences with a given tone-interval. Yet she was slower than controls with incongruent tastes applied to her tongue. In contrast, the different tastes didn't affect the control musicians' performance.

"This demonstrates that synaesthesias may be used to solve cognitive problems", Gian Beeli and his colleagues said.

Moreover, when the researchers presented E.S. with single taste-related words (rather than applying actual tastes to her tongue), they had no effect on her tone-interval Stroop task performance – thus suggesting strongly that the synaesthesic effect was sensory, not conceptual, and occurred via cross-talk between her auditory and gustatory senses.

There is a downside for E.S. though. According to New Scientist magazine, her synaesthesia affects her musical choice – for example, Bach's music is a favourite because it's particularly creamy.
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Beeli, G., Esslen, M. & Jancke, L. (2005). When coloured sounds taste sweet. Nature, 434, 38.