People with arachnophobia tend to feel uneasy in any area they believe could harbor spiders or that has visible signs of their presence, such as webs. If arachnophobics see a spider, they may not enter the general vicinity until they have overcome the panic attack that is often associated with their phobia. Some people scream, cry, jump from moving cars, trouble breathing, have excessive sweating or even heart trouble when they come in contact with an area near spiders or their webs. In some extreme cases, even a picture or a realistic drawing of a spider can also trigger fear.
An evolutionary reason for the phobias remains unresolved. One view, especially held in evolutionary psychology, is that the presence of venomous spiders led to the evolution of a fear of spiders or made acquisition of a fear of spiders especially easy. Like all traits, there is variability in the intensity of fears of spiders, and those with more intense fears are classified as phobic. Spiders, for instance, being relatively small, do not fit the usual criterion for a threat in the animal kingdom where size is a factor, but can be venomous.
The alternative view is that it is lit the dangers, such as from spiders, are overrated and not sufficient to influence evolution. Instead, inheriting phobias would have restrictive and debilitating effects upon survival, rather than being an aid. For some communities such as in Papua New Guinea and South America (except Chile, Colombia, Costa Rica, Brazil, Uruguay, Argentina and Bolivia), spiders are included in traditional foods. This suggests arachnophobia may be a cultural, rather than genetic trait.