Phobias and the Brain
You are in an airport waiting for your plane to arrive. You've never flown before, and are more terrified than you can ever remember being. Everyone has told you the supposedly comforting statistics - "millions of planes take off each day and there's only a handful of crashes," "flying is safer than driving." You know rationally that there is no reason to be so scared, but regardless your heart is racing, your palms are sweating, and you're light-headed. Simply the thought of being up in the air, out of control, makes you feel faint. Finally the flight attendant announces that your plane has arrived. But as all the other passengers line up to get onboard, you grab your luggage and walk straight out of the airport, with every step feeling more and more relieved. What is this feeling of anxiousness? Why can't you get rid of it even though you consciously know that it is irrational? What is it caused by? How can it be prevented or lessened?
What you experienced in the airport is a phobia. A phobia is the sensation of extreme fear "when it is not justified by the presence of any real danger or threat, or by any rational cause, and when it is accompanied by a systematic avoidance of the situations that lead to it." (1) A phobia is brought on by a specific stimulus or situation, for example, insects, heights, crowds, or the dentist. Presentation with the fear-inducing stimulus causes a severe anxiety response with very apparent and specific physical manifestations, such as a rapid heartbeat, shortness of breath, trembling, and sweating. Most individuals suffering from phobias are able to recognize that their fear is fundamentally irrational, yet nonetheless go through great lengths to avoid any contact with the given stimulus. (2) Somewhere between 5.1% and 12.5% of Americans have experienced some sort of phobia. (3) Women are two to three times as likely to have phobias than men. There are three basic kinds of phobias: agoraphobia (fear of situations in which escape may be difficult), social phobia, and specific phobias. The DSM-IV has separated phobic stimuli into four basic categories: animal, situational, blood injury, and nature-environment. (3)
Though the experience of phobias is relatively common and their physical characteristics are generally well understood, there is no real consensus on the neurobiological basis of phobias. Instead, there are currently several different models and theories that work to try to understand how and why phobias occur in the human brain. Most hypotheses regarding phobias take a different approach, from biological to psychoanalytic to evolutionary. Is there one model that seems "less wrong" or more satisfying in our efforts to understand the biology of phobias? Using the various models, how do phobias seem to come about? How does thinking about phobias add to our understanding of the brain and behavior?
The classical conditioning model was one of the first theories used to...