Abstract
The goal of this paper was to describe and evaluate the effectiveness of a self-managed behavior modification plan that included token-based DRO intervention aimed at decreasing habitual nail biting behavior. A comprehensive functional behavior assessment was conducted using several indirect and direct methods to determine an underlying function of the nail biting behavior. Results of the record review, behavioral interview and the A-B-C charts indicated that nail biting was automatically reinforced. Based on these results, a differential reinforcement of other behavior intervention paired with token economy was selected and implemented. Details regarding this intervention protocol are discussed as well as evaluation of its effectiveness after two weeks of implementation. Finally, a potential advantages and disadvantages of selected approach are presented as well as ethical issues that apply to this particular case.

Keywords: nail biting, DRO, token economy, behavior modification plan, functional analysis

The goal of the present paper is to describe and evaluate the effectiveness of a self-managed behavior change intervention aimed at decreasing habitual nail biting behavior. The habitual nail biting behavior is very common in children and adolescents (Christmann & Sommer, 1976) and, in some cases, it can continue into adulthood (Ballinger, 1970). Nail biting prevalence is at peak during adolescence (at 45%). It gradually increases during childhood, but after adolescence it decreases to approximately 4.5% prevalence during adulthood, with females engaging in nail biting more than males (Ballinger, 1970). Nail biting is usually nothing more than a nuisance and does not cause impairment. However, in most severe cases it can lead to more serious medical issues, such as tissue damage, skin infections or teeth root damage, or even social and psychological issues, such as increased self-consciousness (Silber & Haynes, 1992).
My goal was to put to extinction or at least maximally decrease my habitual nail biting behavior. This was important to me for several reasons. First, studies have shown that habitual nail biting can lead to more serious consequences for the individual, such as long lasting physical impairment, if not properly addressed and treated (Long et al. 1998). As a type of self-injurious behavior that is usually maintained by automatic reinforcement, it can be very difficult to treat if an effective replacement behavior has not been identified that can substitute the function of the nail biting behavior (Cowdery et al. 1990). The habitual nail biting can be very challenging to address because individuals often minimize its clinical significance (Cowdery et al. 1990). Finally, in addition to health concerns, this was important to me due to aesthetic reasons.

In my previous paper, I discussed in detail the first part of creating the behavior change plan that is based on an underlying function of behavior, in this case, my nail biting. I will summarize the most important steps preceding the actual intervention implementation in the following passages.

First, I needed to conduct a comprehensive Functional Behavior Assessment, by reviewing medical history records, conducting a behavioral interview, a direct

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