If you’ve ever clenched up at the sound of nails on a chalkboard, or felt a pleasant chill when listening to an opera soprano, then you have an intuitive sense of the way our brains sometimes mix information from our senses. For the latest issue of Nautilus magazine I wrote a story about a woman whose brain mixes more than most, allowing her to feel many types of sounds on her skin.

Over the past decade or so, neuroscientists have revamped their view of how the brain processes sensory information. According to the traditional model, the cortex, or outer layers of the brain, processes only one sense at a time. For example, the primary visual cortex at the back