se in an organism is associated with an unconditioned stimulus (US), an event that automatically or naturally causes a response (Bourne & Russo, 1998). This association causes the response to the US, the unconditioned response (UR), to transfer to the neutral stimulus (Bourne & Russo, 1998). The US no longer needs to be there for the response to occur in the presence of the former neutral stimulus. Given that this response is not natural and has to be learned, the response is now a conditioned response (CR) and the neutral stimulus is now a conditioned stimulus (CS) (Bourne & Russo, 1998). In Pavlov's experiment a tone was the neutral stimulus that was associated with the US of food. The UR of salivation became a CR to the newly CS of the tone (Schwartz & Robbins, 1995). The function of the Pavlovian model of classical conditioning is primarily to assist an organism in "preparing" for some forthcoming important event (Kalat, 1998). Classical conditioning when applied to phobias, postulate that the response of phobic fear is a reflex acquired to non-dangerous stimuli. For example the normal fear to a dangerous stimulus, such as a poisonous snake, has been over generalised to non-poisonous snakes as well. However Ohman & Soares (1993) maintain classical conditioning does not account for the disassociation between cognitions and conditioned behaviour.
             According to Marks (1989) most dangers that humans are likely come across have already been encountered by our ancestors. In the past, those who responded to danger lived longer and had more descendants. Marks (1989) describe prepotency as a physiological system that makes an organism respond attentively to certain cues. Further, organisms are predisposed to learn certain reactions to particular stimulus, such as fear rather than nausea is the reaction to snakes and heights where as rotting food would e
             ...