Spontaneous sensations are such a common phenomenon that anyone may feel them at any time, provided attention is oriented towards, and kept on a part of the body. It was their subjective nature, a core definition of interoception, which for a long time prevented scientific and detailed investigation [19]. Even though recent investigations provide us with tentative information about the cognitive and neural mechanisms underlying SPSs [2–4,26,27,39], they tell us little about the functions
these may serve.