so aaron beck a number of years ago identified a host of cognitive behavior treatments. showing that exposure therapy tends to work particularly well and people with fear-related disorders. and exposure therapy is enter where we teach the brain to no longer be afraid. in a rat model if we did what we call extinction of fear, again, the same pavlov, who coined the term extinction over a hundred years ago. he would take the dog afraid of a cue or a dog salivated and give them the cue over and over again in the absence of the reinforcer, whether it's the positive thing or negative thing. >> rose: and they lost the here? >> they appear to lose it. >> rose: loss of physical reaction. >> exactly. and we think that by exposing the vietnam rhett ran to their memories of the fear and trauma, exposing the phobic patient to the tarantula or the snake, exposing the fear of public speaking person to give public speeches, doing this a few times is sometimes not enough. and sometimes it can exacerbate the anxiety. but if you do it enough the proper way with exposure therapy you extingu