As the name implies, people with a specific phobia generally have an irrational fear of specific objects or situations. The disability caused by this phobia can be severe if the feared object or situation is a common one.

A frightening or threatening experience with an animal or in a particular situation can cause a specific phobia. For instance, someone who has been bitten by a vicious dog may generalize their fear to include all dogs, regardless of the animals' dispositions.

Fear can be learned from others as well. For instance, the child of a parent who responds with intense fear and anxiety whenever they encounter a harmless garden snake learns to respond to snakes with the same fear and anxiety.

The most common specific phobia in the general population is fear of animals—particularly dogs, snakes, insects, and mice. Other specific phobias are fear of closed spaces (claustrophobia) and fear of heights (acrophobia).

Most simple phobias develop during childhood and eventually disappear. Those that persist into adulthood rarely go away without treatment.