When your child has the urge to bite his nails, have him try this instead:

In three minutes or less, the urge to bite the nails should disappear, says psychologist Nathan H. Azrin. No need to watch a clock; just approximate it. Watching the clock would only serve to distract the child from his activities.The amount of pressure exerted should be great enough so that the child can distinctly feel the pressure on his finger, but never press so tightly that it causes tension or strain.

Watching TV: Grasp the armrests (if any) of the chair or sofa; or rest hands on thighs.

Playing a board game: Grasp the edge of the table, edge of the game board or a score pad and pencil.

Reading a book, magazine or newspaper: Hold each half of the book or magazine firmly with both hands, or hold the sheets of the newspaper with both hands.

Doing homework or taking notes in school: Hold the pen or pencil tightly with the writing hand while pressing on top of the paper with all five fingers of the other hand.

Riding as a passenger in a car: Grasp the armrest or the thighs, or carry a book and keep it in the lap and hold onto that.

Speaking on the phone: Hold the receiver firmly with the fingers of one hand while grasping another nearby object with the other, such as a pen, desk, telephone mouthpiece or small ball.

Talking with someone in person: Grasp some part of the clothing such as a belt or pocket. If seated, grasp the knees or the chair's armrests.

Playing with a toy, teddy bear or doll: Hold with both hands.

If no convenient object is available which can be held or pressed in a natural manner, clenching of the hands is almost always possible for use as a "competing reaction," says Azrin.

For clenching, the fingers should be folded with the tips pressing gently against the palm of the hand. The thumb should be on the inside, also pressing gently against the palm. This way, awareness is maintained by the position of finger tips and thumb.

Sitting on the hand is no solution, says Azrin. This prevents your child from going about his usual activities. Besides, it is not considered socially acceptable.

Will your child pick up some other compulsion if he gives up nail-biting? Not likely, says Azrin.

Some statistics on nail-biting

More than half the population is or has been or will be biting their nails, says psychologist Nathan H. Azrin:

* 331/3 percent of children age 6 to puberty

* 45 percent of children from puberty to college age

* 25 percent of college students

* 10 percent of adults over the age 35

Men are as likely to as women to bit their nails, he says, but women are more likely to do something about it because, traditionally, they place greater emphasis on personal appearance.