What is thumb sucking?

Physical and Psychological Factors

It has been estimated that 45 percent of all two-year-olds, 36 percent of four-year-olds, 21 percent of six-year-olds, and 5 percent of eleven-year-olds suck their thumbs. As children grow older, by age five, the occurrence of thumb sucking generally begins to fade during the daytime. If children continue to suck their thumbs, it is generally limited to nighttime.

Thumb sucking seems to be reinforcing to children because of its soothing property. For example, it is often observed among children when they are tired, frustrated, hungry, or uncomfortable, such as when teething causes discomfort. Furthermore, thumb sucking tends to increase the level of independence in infants. This becomes evident when observing an infant who is occupied by this self-stimulating behavior.

Disorders and Effects

Although thumb sucking is relatively harmless among children younger than three years of age, problems can develop if the behavior persists. Negative consequences may consist of dental problems, inhibited speech development, and critical peer and parental reactions.

One of the main problems associated with thumb sucking is dental problems, especially if this behavior persists after the age of four or five. Thumb sucking can also inhibit speech development in formal and informal settings at school or day care. For example, when children are sucking their thumbs during formal group activities, they are less likely to respond to adult questions. Also, during free-play time, children who are sucking their thumbs are less likely to speak spontaneously.

In addition to causing problems for speech and physical development, thumb sucking can create social difficulties for children. According to the Pediatrics article “Influence of Thumb Sucking on Peer Social Acceptance in First-Grade Children,” by P. C. Friman and colleagues, “Social acceptance is lower among children who suck their thumb, and they are viewed by their peers as being less intelligent, happy, attractive, likable, or fun, and less desirable as a friend, playmate, seatmate, classmate, or neighbor.” Furthermore, thumb sucking can create negative interactions between the parents and children. Because parents are often troubled by thumb sucking, children are routinely asked to stop. These requests can be positively reinforcing to the child and can increase the frequency of the behavior.

Given the problems associated with thumb sucking, many parents wonder at what point in time a child should be treated for this behavior. In their 1989 article “Thumb Sucking: Pediatricians’ Guidelines” in Clinical Pediatrics, Friman and B. D. Schmitt provide some guidelines to answer this question. As a simple rule, thumb sucking should not be treated until the potential negative consequences outweigh the benefits, which is seldom before the age of four. When children do suck their thumbs, often it is not frequent enough to warrant treatment. They also point out that at times the potential benefits may outweigh the risks, such as when a child uses thumb sucking as a means of coping with fear, pain, or a significant loss. As suggested by these authors, another indication for treatment is chronic thumb sucking, which they define as occurring “across two or more settings (e.g., home and school) and when it occurs day and night.”

Both positive and negative reinforcement techniques have been used to treat persistent thumb sucking. These include offering other types of stimulation or comfort (depending on whether the cause is boredom or stress), rewarding the child for not sucking his or her thumb, involving the child in breaking the habit, and applying bitter substances to the thumb as a deterrent. As with reprimands, the utility and ethics of other negative reinforcements such as bitter coatings continue to be debated.

Perspective and Prospects

Attitudes toward oral behavior in children have fluctuated over the years. It has been viewed as both indulgent and detrimental. There have been high and low attempts to prohibit the activity. Sigmund Freud and his colleagues did much to draw attention to the oral drive in the first year of life, and over the years, many writers have made observations about oral habits and psychological health.

The advent and wide use of pacifiers has done much to neutralize concern over oral behaviors. Pacifiers are generally seen as preferable to the thumb, from a dental perspective. Thumb sucking tends to arouse more anxiety for both parents and medical specialists than does the use of the pacifier; however, pacifier use beyond age four can lead to the same types of dental problems as those caused by prolonged thumb sucking.

Bibliography

American Academy of Pediatrics. "Pacifiers and Thumb Sucking." HealthyChildren.org, May 11, 2013.

A.D.A.M. Medical Encyclopedia. "Thumbsucking." MedlinePlus, January 24, 2011.

Berk, Laura E. Child Development. 8th ed. Boston: Pearson/Allyn & Bacon, 2009.

Friman, P. C., K. M. McPherson, W. J. Warzak, and J. Evans. “Influence of Thumb Sucking on Peer Social Acceptance in First-Grade Children.” Pediatrics 91, no. 4 (April, 1993): 784–86.

Leach, Penelope. Your Baby and Child: From Birth to Age Five. Rev. ed. London: Dorling Kindersley, 2010.

Nathanson, Laura Walther. The Portable Pediatrician: A Practicing Pediatrician’s Guide to Your Child’s Growth, Development, Health, and Behavior from Birth to Age Five. 2d ed. New York: HarperCollins, 2002.

“Thumb Sucking and Teeth.” Pediatrics for Parents 19, no. 12 (2002): 1–2.

"Thumb Sucking: Help Your Child Break the Habit." Mayo Foundation for Medical Education and Research, September 20, 2012.

Van Norman, Rosemary. Helping the Thumb-Sucking Child. Garden City Park, N.Y.: Avery, 1999.

Walker, C. Eugene, and Michael C. Roberts, eds. Handbook of Clinical Child Psychology. 3d ed. New York: John Wiley & Sons, 2001.