Escape conditioning is the term used to describe a subject's or animal's avoidance of stimuli, usually as a result of negative experiences, which leads to the behavior. If a person had a bad experience while swimming in the ocean, for example, leaving or avoiding any situation that involved going into the ocean again is a form of escape conditioning.
Escape conditioning is part of what is called aversive conditioning. This is defined by the subject removing itself from the situation or stimulus.
Another form of aversive conditioning is avoidance conditioning. This is similar to escape conditioning, although slightly different in some respects.
The main difference between escape conditioning and avoidance conditioning is that a conditioned stimulus will be presented to the subject before the averse stimulus. This acts as a trigger for avoidance behavior, once the association is made. A light, sound or other signal is often used to precede a stimulus; this is usually a harmless electric shock in the case of animals.
Once the association is made between the conditioned stimulus and the averse stimulus, the subject will act in avoidance before the averse stimulus is present. This can often be seen in human behavior, with examples ranging from avoiding the doctor until there is no alternative, to finding other activities to do instead of an unpleasant activity.