Both forms of fear can be deranged. Instinctive anxiety is pathological when it is excessive and persistent enough to paralyze action. Learned anxiety is pathological when it is provoked by events that present no real threat, as when a neutral stimulus comes to be associated in the brain with instinctive anxiety. Anxiety states were of particular interest to me because they are by far the most common mental illnesses: at some point in their lives, 10 to 30 percent of people in the general population suffer from these anxiety disorders!
