Coping strategies to adapt to environmental and psychological contingencies have been well studied in the human subject. The typical individual is known to have response patterns that permit automatic, and often unconscious adjustment to changing conditions. Psychological (defence) mechanisms facilitate adaptation to new situations or interactions, and when successful, no additional coping mechanisms need to be invoked. However, situations may arise when such mechanisms are insufficient: this may result from developmental failure, personality factors, inordinate levels of stress, or combinations thereof.