Some people can raise goose bumps at will, and most never realise it's rare
A small, unmeasured share of people can summon goose bumps on command, with no cold, fear or music to trigger them. The knack seems to be inborn rather than learned, tends to go with a personality open to new experiences, and those who have it often assume everyone else can do it too.
Goose bumps appear when tiny smooth muscles called arrector pili, anchored at the base of hairs, contract and pull the hairs upright. The sympathetic nervous system, the same wiring behind fight-or-flight, sets this off. Scientists once assumed each muscle served a single follicle; newer work shows one muscle can connect to several. Formally the reflex is called piloerection, or more traditionally horripilation.
In furry animals the purpose is clear. Raised hair traps air for insulation, and it makes an animal look bigger to a rival, as seen in frightened cats, stressed rats and the displays of chimpanzees. Porcupines raise their quills on the same principle. In humans, with little hair to fluff, the reflex is often called vestigial, though it does coincide with changes in skin temperature.
People get them from cold, tickling, fear, a winning moment in sport, a horror film or fingernails on a chalkboard. Emotional or thermal triggers tend to spread them over the whole body, while touch raises them only locally. Yet feelings and skin do not always match: studies find that people who report goose bumps or musical chills often show no measurable piloerection. One virtual-reality study that filmed participants' arms found 43.8% developed goose bumps while exploring Earth, and those who did rated their sense of awe higher.
Language adds its own quirks. English and many European tongues picked the goose, whose plucked skin shows bumps where feathers were; French, Spanish and Japanese choose the hen, Hebrew the duck, and Russian and Ukrainian speak of ants crawling on the skin. The phrase cold turkey may come from the gooseflesh of abrupt opioid withdrawal, which resembles a chilled plucked bird. Piloerection can also be a symptom of temporal lobe epilepsy and some brain tumours.
Source: Goose bumps
