RESISTANCE TO EXTINCTION OF FEAR-RELEVANT STIMULI - PREPAREDNESS OR SELECTIVE SENSITIZATION

Human conditioning research has revealed an apparent resistance to ext inction of aversive conditioning to pictures of fear-relevant stimuli such as snakes and spiders, supporting M. E. P. Seligman's (1971) prep aredness theory of fears and phobias. This article examines an alterna tive account based on activation of preexisting response tendencies un der threat (selective sensitization). Two experiments demonstrate that selective sensitization of electrodermal responses is attenuated when a fear-relevant stimulus serves as a negative conditioned stimulus (C S-), but is maintained when it serves as a positive conditioned stimul us (CS+). Previous extinction results may therefore be due to preserva tion of initial responding to CS+ but not CS-. Selective sensitization offers a model for the nonassociative activation of fears and phobias to prepotent stimuli under conditions of stress or threat. Possible g enetic and cognitive mechanisms are discussed.