Fear results in selected behaviors that are comparable
across species such as fight, flight, or freeze motoric behaviors; piloerection; defecation;
autonomic changes; and adrenal hormone release. Pain is viewed as a moti vated, competitive system
and distinct from fear. That is, the simultaneous experiences of fear and pain are incom patible;
a fear experience releases endorphins (Bolles & Fanselow, 1980). Fear must be expressed; its
expression provides an opportunity for the organism to be in a ready state for future stimuli.
Generally, most fears are learned (Davis, 1997) and reflect an association between neutral events
and an aversive stimulus. Fear memories