Phobias are persistent and irrational fears elicited by specific stimuli such as spiders or confined spaces. The perceived danger theory proposes a dual belief system in which phobic people believe that nothing bad will happen to them if they do what they fear (e.g. touched a spider) but they persistently avoid doing so (Williams, Kinney, Harap and Liebmann 511). Other theories are that phobia results from anticipated anxiety in which a phobic escapes a situation to avoid feeling afraid, and the self-efficacy theory which is that avoidance arises from a strong belief that the person cannot carry out the avoided activity.
SeligmanÆs preparedness hypothesis states that ôevolutionary pressures select for an adaptive predisposition to associate fear with potentially dangerous stimuliö which would explain why some phobias, such as fear of spiders and snakes, are more widespread in the population than phobias of more evolutionary recent things such as cars and dentists (Mulkens, de Jong and Merckelbach 464). However, another model suggests that phobia of spiders is due to a disgust sensitivity because spiders are associated with dirty places: the disease-avoidance model.
Elevated disgust sensitivity is also considered to be the vulnerability factor for blood-injection-injury phobia, which shares many characteristics with other specific simple phobias (Schienle et al 87). However, while these other phobia sufferers show marked and persistent fear during the anticipation and appearance of the phobic stimulus and try to avoid the situation, other characteristics are very specific for blood-injection-injury phobics. These phobics show a distinct autonomic response pattern with parasympathetically dominated cardiovascular responses involving an initial brief heart rate acceleration and blood pressure increase, followed by a steep decrease in both measures, which can provoke fainting. These phobics also exhibit an elevated s...