which makes the muscles attached to the base of each hair follicle contract and force the hair up. Music Canadian researchers have suggested that when humans are moved by music, their brains behave as if reacting to delicious food, psychoactive drugs, or money. The pleasure experience is driven by the chemical dopamine, which produces physical effects known as "chills" that cause changes in heart-rate, breathing, temperature and the skin's electrical conductance. The responses correlate with the degree to which people rate the "pleasurability" of music. Dopamine release is greatest when listeners have a strong emotional response to music. "If music-induced emotional states can lead to dopamine release, as our findings indicate, it may begin to explain why musical experiences are so valued", wrote the scientists. Ingestion Medications and herbal supplements that affect body temperature and blood flow may cause piloerection. For example, one of the common reported side effects of the intake of yohimbine is piloerection. Opiate withdrawal Piloerection is one of the signs of opioid withdrawal. The term "cold turkey" meaning abrupt withdrawal from a drug, may derive from the goose bumps that occur during abrupt withdrawal from opioids; this resembles the skin of a refrigerated plucked turkey. Voluntary control An unknown proportion of Cambodian nerves of people may consciously initiate the sensation and physiological signs of piloerection. The phenomenon is discovered spontaneously, appearing to be innate, and is not known to be possible to learn or acquire. Those with the ability frequently are unaware that it is not possible for everyone. The ability appears to correlate with personality traits associated with openness to experience. Primate heritage hypothesis People often experience goose bumps as a reaction to the sound of fingernails being dragged across a chalkboard. In 2006 Vanderbilt psychologist Randolph Blake conducted a study to find out why people react that way to the sound. He noted that the core sound causing the reaction was acoustically similar to that of a primate distress call. Etymology The term "goose bumps" derives from the phenomenon's association with goose skin. Goose feathers grow from pores in the epidermis that resemble human hair follicles. When a goose's feathers are plucked, its skin has protrusions where the feathers were, and these bumps are what the human phenomenon resembles. It is not clear why the particular fowl, goose, was chosen in English (and German, Greek, Italian, Swedish, Danish, Norwegian, Polish and Czech) as most