Child psychiatrists know that children are vulnerable to what they call post-traumatic or delayed stress. Sometimes, when their normal defense mechanisms are unable to deal with a particularly frightening or traumatic situation, their behavior may change, become weird, bizarre, or inexplicable. They may be unable to communicate their fears -- the abused child rarely complains first, for example -- and fear may surface in later life as a serious personality disturbance or severe emotional distress.

San Francisco child psychiatrist Dr. Lenore Terr lists these signs of a child being in possible trouble:

* The same nightmare. (Not just recurrent dreams, but ones of real terror.)

* A compulsion to play the same imaginary, possibly weird game over and over. (Not board games, but those with dolls or other toys that tell the same story again and again.)

* Unaccountable behavior. Terr recalls a 4-year-old who appeared terrified of his nursery-school graduation. After questioning it was learned that the aisle down which the children would walk somehow reminded him of an elevator he'd been stuck in.

* Personality changes. If a normally independent child becomes clinging -- or vice versa. Or if there is unusual aggression, irritability, anger or babylike behavior.

These do not suggest necessarily that the child is ill -- only that there may be a problem he cannot cope with all by himself.