startle reaction


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startle reaction

 [stahr´t'l]
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.

star·tle re·flex

a primitive reflex response observed in the normal newborn but typically suppressed by 3-4 months of age. Any sudden stimulus (for example, a loud noise, a blow to the supporting surface, or being dropped 5-10 cm through space) causes flexion of the hip and knee joints with fanning of the fingers followed by fist clenching and extension of the upper limbs followed by flexion. Synonym(s): Moro reflex, parachute reflex, startle reaction
See also: cochleopalpebral reflex.

startle reaction

the mental state of suddenly aroused awareness; manifested by a flight or fight or submit pattern of behavior and posture.
References in periodicals archive ?
With emotions such as surprise, happiness and disgust, note the researchers, facial expressions can be inhibited and simulated fairly successfully and are far more difficult to elicit experimentally than is the startle reaction.
Still, children with or without disabilities can be expected to demonstrate continuing confusion about events, startle reactions, worry (clinging in young children), sadness, anger, fear, or preoccupation.
1996), whereas sperm whales showed strong startle reactions, occasionally involving defecation (Whitehead et al.