title: When good things go bad: the reflex physiology of defense.
abstract: For humans, the threat of painful shock greatly potentiates the reflexive startle blink. Moreover, viewing unpleasant, compared with pleasant, pictures also prompts heightened startle reflexes, suggesting that the startle reflex indexes general defensive activation. In this study, pleasant or unpleasant pictures were used to signal shock threat in order to explore how previous affective associations modulate new defensive reactions. When cuing threat of shock, pleasant and unpleasant pictures prompted physiological profiles consistent with defensive activation, indicating that threat of shock renders previously pleasant cues aversive. For unpleasant pictures only, defensive startle was potentiated even when these cues signaled safety. Taken together, the data indicate that (a) regardless of their intrinsic affective meaning, cues signaling shock threat prompt somatic and autonomic reactions consistent with defense, and that (b) intrinsically unpleasant cues continue to prompt defensive activation even when the context of their presentation is specifically non-threatening.
authors.affiliation: University of Florida, USA. bradley@ufl.edu
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Bradley
authors.forename: Brad
authors.initials: B
authors.lastname: Moulder
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lang
mesh_terms: D000328:Adult; D000339:Affect; D001244:Association; D001919:Bradycardia / Q000503:physiopathology; D003463:Cues; D003674:Defense Mechanisms; D004576:Electromyography / Q000379:methods; D005149:Facial Expression; D005152:Facial Muscles / Q000502:physiology; D005239:Fear; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology; D006801:Humans; D008297:Male; D012018:Reflex / Q000502:physiology*; D013216:Reflex, Startle; D017603:Signal Detection, Psychological; D014796:Visual Perception