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A Behavior Modification Plan to Decrease Nail Biting
Camila Leyva
School of Behavioral Science, Liberty University
PSYC 320: Behavior Modification
Professor Shadoan
June 2, 2025
Introduction
Onychophagia or nail biting is a common body-focused repetitive behavior beginning
during late childhood and persisting into adulthood. Despite often being described as a
harmless habit, chronic nail biting leads to physical damage to nails and skin and an increase in
infection risk and social stigma. Chronic nail biting, according to Roberts et al. (2013), has an
emotional consequence of lowering levels of self-confidence and esteem. I have been affected
by the behavior myself for a number of years now, and it has been worse when I feel stressed,
bored, or focused. My goal in this project is to decrease the frequency of my nail biting through
the use of a behavior modification strategy supported by psychological research. This essay
synthesizes existing evidence about nail biting and presents an evidence-based intervention to
reduce it.
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My target behavior is operantly defined as inserting one or more of my fingers into my
mouth and biting or ripping at the nail or cuticle upon it by using my teeth. The target behavior
is observable and quantifiable by measuring each incidence of nail biting during each daily
period using a self-monitoring log. Additionally, I will introduce a replacement behavior, such as
using a stress ball or chewing gum, to occupy my hands and mouth during moments of
temptation. This treatment method is grounded in behaviorist principles and has been shown to
be effective in reducing similar habits.
Section I: Target Behavior and Supporting Research
Nail biting is a recurring body-focused behavior (BFRB), which develops early during life
and continues into adulthood. Onychophagia is largely initiated by emotional states of stress,
anxiety, and boredom and can be a soothing habit under states of stress or leisure.
Onychophagia consists of ritualized repetition of nail biting and can cause physical
consequences like infections, dental issues, and stigma (Ghanizadeh, 2011).
Researchers have employed several methods of assessing the rate and amount of nail
biting. In addition to self-report diaries, which provide subjective data, researchers use direct
observational techniques such as video recordings and behavioral checklists to objectively
capture the behavior in real-time and across different settings (Pacifico et al., 2024). These
assessments are a more valid measurement of behavior rate and amount.
Biting nails is a common habit found among children and adults. According to reports,
30% of children, 45% of teenagers, and 20–25% of young adults are nail-biters (Baghchechi et
al., 2020). Even though it tends to begin early, it peaks during adolescence and continues
through adulthood if not treated. Onychophagia is common among perfectionists, those who
have ADHD (attention-deficit/hyperactivity disorder), and people who have anxiety disorders,
which indicates that there could be an association between onychophagia and intrinsic
psychiatric disorders (Pacan et al., 2014).
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While regularly watered down as a harmless or superficial behavior, chronic nail biting
has both physical and emotional implications. Physically, chronic nail biting can cause side
effects such as damage to nail bed, cuticles, and surrounding skin, making the individual
vulnerable to bacterial and viral infections. Frequent biting can further cause dental
complications such as malocclusion or chipped or broken teeth. Emotionally, such an individual
feels guilty, embarrassed, and develops social anxiety due to the very unpleasant view of bitten
nails, which are likely to affect confidence and social interaction. Chronic nail biting, overtime,
can strengthen maladaptive response patterns, and such an individual would be unable to
acquire adaptive methods of dealing with emotional stressors (Halteh et al., 2016).
Reducing or eliminating nail biting can have several positive outcomes. Physically, it
prevents damage to nails and surrounding skin, preventing infection and leading to healthier
nails. Psychologically, the patient feels no longer ashamed or embarrassed about how their
hands appear, leading to improved self-esteem and interpersonal relationships. Moreover, by
treating the emotional etiologies, the patient is likely to have improved emotional control and
coping mechanisms (Ghanizadeh, 2011).
Several key nail-biting variables have been identified through research. Emotional
precursors such as boredom, stress, and anxiety are often characterized as preceding the
behavior. Nail biting is commonly comorbid with such other BFRBs as hair pulling and skin
picking, which speaks to comparable mechanisms. The observations underscore the need to
consider emotional and behavioral variables when developing effective intervention for nail
biting (Roberts et al., 2013).
Section II: Treatment Method and Supporting Research
I will be treating my nail biting using an intervention based on positive reinforcement
and habit reversal training (HRT). Positive reinforcement involves presentation of a reinforcing
stimulus after a target behavior and has the outcome of making the behavior's recurrence more
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likely (Miltenberger, 2016, p. 70). In this context, the desired behavior is abstaining from nail
biting, and the rewarding stimulus will be a self-selected incentive.
There are findings supporting positive reinforcement in removing body-focused
repetitive behavior (BFRB)s such as nail biting. For instance, Murase et al. (2025) contrasted
positive and negative reinforcement of fingernail biting. Time spent not biting nails produced
tokens which could be exchanged for favorite products given to the subject. The positive
reinforcement condition produced steadier decreases in nail-biting than did the negative
reinforcement condition.
Additionally, habit reversal training (HRT) has been identified as an effective behavioral
therapy for BFRB. HRT has several components such as awareness training, competing response,
and social support. The application of HRT through a clinical trial revealed lowered rates of nail
biting compared to control groups (Ghanizadeh et al., 2013). Activating an alternative behavior
for nail biting that is incompatible with nail biting (e.g., fist clench or object hold) proved to be
very effective.
Another study by Heffernan and Lyons (2016) explored the application of differential
reinforcement of other behavior (DRO) to reduce excessive nail biting. Treatment involved
granting access to reinforcement stimuli for not engaging in nail biting for specific intervals. The
result revealed the decrease in frequency of nail biting and proved that reinforcement of
alternative behavior can be an effective method to reduce the target behavior.
Using these findings to implement my personal behavior change program, I will utilize a
daily self-monitoring system, an app or diary for each occurrence of nail biting and occasions of
no nail biting. This program will be carried out over the course of two months to allow for
consistent tracking and gradual improvement. I will reward myself for each successful day of not
nail biting by engaging in an enjoyable activity or receiving a special gift. To implement the
competing response factor of HRT, I will identify alternate activities and behaviors to utilize if
and when the urge to nail bite arises, such as utilization of a stress ball or sucking on sugar-free
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gum. This structured program will replace healthy behavior for nail-biting behavior, positively
reinforced regularly.
Through positive reinforcement and habit reversal techniques, I expect nail biting to
reduce over time and therefore have healthier nails and overall wellbeing.
Conclusion
The behavior that I have chosen to reduce in this project is nail biting, a body-focused
repetitive behavior often preceded by boredom, anxiety, or stress. I have chosen to reduce this
behavior since it has negative effects on my appearance, exposes me to a higher risk of
infection, and displays a general lack of self-control. To reduce this behavior, I plan to employ
positive reinforcement and habit reversal training, which are both empirically based and
grounded principles in behavioral science. My plan is to monitor daily behavior and reward
myself if I reduce it, and replace nail biting with alternative and healthier reactions such as
stress ball use.
I plan to monitor improvement of this behavior shift by weekly nail-biting counts and
measures of improvement in nail condition and self-esteem. Maintenance after a period of time
will be promoted through continued reinforcement and response substitution contingency
management on a need-based basis. Following regular utilization of these approaches, I expect
systematic decreases in incidence of nail-biting and enhancement of overall self-regulation, to
my health and personal contentment.
References
Baghchechi, M., Pelletier, J. L., & Jacob, S. E. (2020). Art of Prevention: The importance of
tackling the nail biting habit. International Journal of Women’s Dermatology, 7(3),
309–313. https://doi.org/10.1016/j.ijwd.2020.09.008
Ghanizadeh, A. (2011). Nail biting; Etiology, Consequences and management.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3556753/
Ghanizadeh, A., Bazrafshan, A., Firoozabadi, A., & Dehbozorgi, G. (2013). Habit
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Reversal versus Object Manipulation Training for Treating Nail Biting: A Randomized
Controlled Clinical Trial. https://pmc.ncbi.nlm.nih.gov/articles/PMC3796295/
Halteh, P., Scher, R. K., & Lipner, S. R. (2016). Onychophagia: A nail-biting conundrum for
physicians. Journal of Dermatological Treatment, 28(2), 166–172.
https://doi.org/10.1080/09546634.2016.1200711
Heffernan, L., & Lyons, D. (2016). Differential reinforcement of other behaviour for the
reduction of severe nail biting. Behavior Analysis in Practice, 9(3), 253–256.
https://doi.org/10.1007/s40617-016-0106-3
Miltenberger, R. G. (2016). Behavior modification: Principles and procedures (6th ed.).
Cengage Learning.
Murase, E. M., Raygani, S., & Murase, J. E. (2025). Narrative Review of Internet-Based
Self-Help Tools for Body-Focused Repetitive Behaviors: Recommendations for Clinical
Practice. Dermatology and Therapy. https://doi.org/10.1007/s13555-025-01380-8
Pacan, P., Grzesiak, M., Reich, A., Kantorska-Janiec, M., & Szepietowski, J. (2014).
Onychophagia and onychotillomania: prevalence, clinical picture and comorbidities. Acta
Dermato Venereologica, 94(1), 67–71. https://doi.org/10.2340/00015555-1616
Pacifico, A., Iorizzo, M., Pasch, M., Kridin, K., Del Fabbro, M., Mercuri, S. R., Peluso,
L., & Damiani, G. (2024). Telemedicine in Nail Psoriasis: Validation of a New Tool to
Monitor (In-Person, In-Picture, and In-Video) Nail Psoriasis Severity in Patients with
Concurrent Onychophagia and Onychotillomania. Dermatology and Therapy, 14(5),
1161–1172. https://doi.org/10.1007/s13555-024-01160-w
Roberts, S., O’Connor, K., & Bélanger, C. (2013). Emotion regulation and other
psychological models for body-focused repetitive behaviors. Clinical Psychology Review,
33(6), 745–762. https://doi.org/10.1016/j.cpr.2013.05.004
