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LONDON Hearing a word usually conjures up an image but some people can begin to taste the word even before it is spoken.
They have a rare form of synaesthesia, or crossing of the senses, where the taste of the word is triggered by its meaning, scientists said.
"Basically hearing words, saying words or reading words triggers a complex sensation of taste in the mouth," said Julia Simner of the University of Edinburgh in Scotland.
Synaesthesia usually runs in families. About one in 23 people have some form of crossed sensory experience but in most cases people experience colours when they hear a letter or number.
"This word-taste variant within synaesthesia is so unusual we don't have a good idea of how common it is," said Simner.
She travelled about 14,480km from Scotland to England and across the United States to find six people with word-taste synaesthesia for a study published in the journal Nature.
Scientists know synaesthesia is genuine and the sensations are automatic because they can see them being triggered in the brain by using sophisticated imaging techniques.
When Simner and her co-author Jamie Ward showed unusual objects to the synaesthetes and asked them to name them the researchers found that the taste was triggered by the meaning of the word and not the sound.
The synaesthetes started to taste the word before they started to say it.
"You have to access the meaning of the word to have the taste triggered," Simner said.
"It is triggered by the part of the brain that encodes the meaning of words, not the part of the memory that encodes the way the word sounds."
Simner said synaesthesia is caused by parts of the brain that don't normally actively communicate with each other. The same connections exist in the brains of most people but they are inhibited so the information is not allowed to pass.
"We suspect that in synaesthesia those pathways are opened up and information can pass down them," she added.
- REUTERS
