THE CONDITIONING BIAS TO

In classical fear conditioning, a neu-tral stimulus, once paired with an aver-sive event for several times, can induce fear reaction by itself. Compared with fear-irrelevant stimuli such as birds and butterflies, fear-relevant stimuli such as spiders and snakes are more readily asso-ciated with aversive events. This prepared learning phenomenon is highly resistant to extinction, insensitive to cognitive manip-ulations, and could be acquired in only one trial (Seligman, 1971; Öhman and Mineka, 2001). From an evolutionary per-spective, human beings and non-human primates are predisposed to learn to fea