It seems that one of the major problems new trainees have is giving up from a simple pin due to a severe anxiety response. Claustrophobia, or fear of tight/enclosed, spaces is actually quite common. It is also commonly experienced when a new trainee gets pinned on the bottom.
The sensation of being on the bottom often combines claustrophobia with other fears. First there is pressure on the chest that interferes with breathing and induces a sensation of dyspnea (shortness of breath). Even mild dyspnea can trigger panic because sudden loss of breath is one of those deeply-rooted human fears. Second there is the mild sensory deprivation. Many times a pin involves someone crushing your face with his or her body. This deadens sound and blocks sight and in many cases the gi acts as a sort of hood. Hooding is a common method of psychological torture and some have argued its use with prisoners of war is in violation of the Geneva Convention. Whatever your thoughts are on this particular issue, it is impossible to argue that it can invoke a feeling of panic and suffocation.
These are all issues that new grapplers must learn to deal with if they are to continue. In researching this topic I found that Stephen Kesting had already posted a great article on this on his website. Instead of writing another article I will just post a link to his. This is a great article for novices but also for coaches who need to help their students get through this fear.
Brian Jones, PhD