A phobia is an extreme fear which most people know is irrational but they are unable to control their response when confronted with the object of their fear.  Phobias can occur in varying degrees.  For example, a person afraid of snakes may be unable to:

 

• Think of a snake
• Hear or say the word 'snake'
• Look at a picture or film of of a snake
• Look at a snake in a safe container
• Touch or handle a snake

 

The typical response to the fear provoking object is avoidance, which in itself reinforces the fear or phobia.  When confronted by a snake (or spider or whatever the feared object is), a phobic reaction could be one of the following:

 

• Screaming or crying
• Freezing on the spot
• Running away

 

Many phobics suffer from panic attacks when in the presence of the feared object.  Symptoms of panic attacks can include one or more of the feelings listed below: 

 

Hot and cold flushes, excessive perspiration, palpitations, tingling in back of neck or hands, restricted breathing, hyperventilating, blurred vision, feeling faint or dizzy.

 

You can find a full list of phobias here