Q: Our 7-year-old son has sucked his thumb forever and more or less constantly. He has recently switched to sucking his index finger and putting his right hand down the back of his pants at the same time. This is driving us crazy.

I read your response to a question recommending “if you catch him sucking his thumb outside his room, confine him to the bathroom for one hour and let him know he can suck all he wants during that time.” We can totally do that at home, but what about school? He is constantly doing it there, including the hand down the pants thing. His teacher tells him to go wash his hands any time she sees it but this has not made a dent in the problem. Help!

A: I developed my hardly-ever-fail thumb-sucking program with my daughter, Amy, who began sucking her thumb within a minute of being born. I think she’d discovered her thumb in utero and used it to pass the time.

At first, it was cute and she cried very little. By the time Amy entered kindergarten, however, her sucking was constant and beginning to be a source of significant irritation for her mother and me. After a lot of trial-and-error (hot sauce, dental appliance, threats of no more birthdays or Christmases, and numerous other equally fruitless approaches), we finally told her she could suck all she wanted in her room, with the door closed, but nowhere else. If we caught her sucking outside of her room, we put her in the downstairs bathroom (smallest room in the house) for an hour during which time she had our permission to suck to her heart’s content.

This approach is a variation on what’s known as a “paradoxical intention.” We gave Amy permission, within a clearly defined boundary, to engage in the unwanted behavior — to suck her thumb. If she crossed the line — in other words, if she sucked anywhere but in her room (and we caught her) — she was sent to bathroom-jail (with the book of her choice), but she could suck all she wanted during her hour of confinement.

Within a relatively short time, Amy got her sucking under control when she was at home (she spent lots of time playing in her room), but we discovered that she was making up for lost time at school. At that point, we developed a daily thumb-sucking report card (on pre-dated index cards) that simply read “Amy did/did not suck her thumb in class today.” At the end of every school day, Amy took the report card to her teacher who checked either “did” or “did not” and signed it.

Amy then brought it home and presented it to us. If the teacher indicated that she did suck her thumb, or if Amy “forgot” the card at school, then she couldn’t watch her favorite, to-die-for television programs after school and had to go to bed an hour early.

I would be remiss if I failed to point out that this approach did not cure her of thumb-sucking. It simply confined it to her room; thus, out of sight, out of mind (more or less). At that point, we were willing to accept mere progress.

Coda: When Amy was 17, I peeked in on her late one night to make sure she’d made it home OK and there she was, pretty as a picture, curled up in her bed, sound asleep with her thumb in her mouth. Some habits die hard.

Family psychologist John Rosemond: johnrosemond.com, parentguru.com.