startle reaction

startle reaction

also called  Startle Pattern,  

      an extremely rapid psychophysiological response of an organism to a sudden and unexpected stimulus such as a loud sound or a blinding flash of light. In human beings it is characterized by involuntary bending of the limbs and a spasmodic avoidance movement of the head. Musculature returns to normal in less than one second, although elevations in heart rate, respiration, and skin conductance persist slightly longer. The startle pattern occurs in all normal humans and all mammals when tested in a relatively uniform manner. The pattern is resistant to extinction or modification by learning, although its intensity may be reduced by repetition or anticipation. The response seems to be an instinctive mechanism for self-defense and, in humans, is probably the initiating element of more general emotional reactions, both motor expressions and conscious experiences. The startle reaction—known as the Moro, or Moro embrace, reflex in children—is particularly conspicuous in infants up to three or four months old.

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Universalium. 2010.

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  • Startle reaction — The startle reaction, also called the startle response, startle reflex or alarm reaction, is the response of mind and body to a sudden unexpected stimulus, such as a flash of light, a loud noise (acoustic startle reflex), or a quick movement near …   Wikipedia

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  • startle reaction — the various psychophysiological phenomena, including involuntary motor and autonomic reactions, evidenced by an individual in reaction to a sudden, unexpected stimulus, as a loud noise …   Medical dictionary

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  • Exaggerated startle disease — A genetic disorder also known as hyperexplexia in which babies have an exaggerated startle reflex (reaction). This disorder was not recognized until 1962 when it was described by Drs. Kok and Bruyn as a disease with the onset at birth of… …   Medical dictionary

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