For a 22-year-old woman known as AW, denim evokes feelings of depression, disgust and worthlessness. Corduroy causes confusion, and silk provides utter contentment. She is one of two people known to experience a newly discovered form of synaesthesia, where textures give rise to strong emotions.
HS, another young woman who experiences tactile-emotion synaesthesia, gets no kick out of denim. Fleece and dry leaves disgust her, while the touch of tennis balls, fresh leaves and sand are heaven.
Other forms of synaesthesia include numbers and letters that evoke colours, shapes that evoke tastes shapes and colours with their very own fragrances.
AW and HS’s sensations, unusual though they may seem, are an extreme form of the positive feelings most people associate with a soft blanket or the aversion to sharp knives and jagged rocks, says V. S. Ramachandran, a neuroscientist at the University of California, San Diego.
"We have an affinity for fur because when were evolving in the ice age, we needed coats," he says. "This is the architecture on which [tactile-emotion synaesthesia] is built."