Stress changes mental and emotional processes, which in turn influence body posture, attitude and general behavior.
How does behavior change during stress? At first, the person's focus is increased on whatever he or she is doing. Because of this focus, social interaction is ignored or downplayed.
As stress becomes prolonged, the focus dissipates while the tension remains. Social interaction cannot be ignored, but due to the tension behavior becomes less considerate and more erratic. The person under stress loses 'the big picture' and jumps from one small thing to another.
As the situation worsens, communication suffers. Because the person is unable to overcome the stress, he or she gets locked into his or her own world of worries. From this stance full of worries every thought, emotion, bodily motion and uttered word becomes tainted with fear, irrationality and confusion.
Many times the stress is caused by social interaction itself. Some people are still able to function socially in a near-breakdown state by creating and showing masks to themselves and others. However, the underlying signs of tension can still be seen by anyone who cares to look.