Chronic skin picking (CSP) is defined as repetitive picking that results in significant tissue damage and is accompanied by marked distress or functional impairment (e.g. Keuthen et al., 2000 and Wilhelm et al., 1999). CSP is not included as a diagnostic category in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR; American Psychiatric Association, 2000) but is most commonly conceptualized as an impulse control (Wilhelm et al., 1999) or obsessive-compulsive disorder spectrum disorder (Stein, Hutt, Spitz, & Hollander, 1993). CSP is thought to occur in 2–4.6% of the population (Arnold et al., 2001 and Keuthen et al., 2001) and is more prevalent among women (Flessner & Woods, 2006).
Phenomenological research suggests that those with CSP vary along different phenomenological dimensions. In semi-structured interviews of 34 adults with CSP, 24% reported full awareness of picking episodes, and 76% said that picking sometimes occurred out of awareness (Arnold et al., 1998). This led Arnold et al. (2001) to categorize CSP into three styles: a “compulsive” style, characterized by picking performed with full awareness and in response to aversive emotions or obsessions; an “impulsive” style, characterized by picking performed with minimal awareness; and a “mixed” style, which shared both compulsive and impulsive features.
Similar dimensions have been proposed and studied in trichotillomania (TTM; repetitive hair pulling), a disorder that is closely linked to CSP (Arnold et al., 1998, Lochner et al., 2002 and Wilhelm et al., 1999). Christenson and Mackenzie (1994) identified “automatic” and “focused” pulling dimensions of TTM. “Automatic” pulling was characterized as pulling that occurred outside of one's awareness, including situations in which an individual pulled while engaged in a sedentary activity, such as reading or watching television. “Focused” pulling was described as more intentional in nature. For example, an individual engaged in “focused” pulling may consciously pull his or her hair in response to an urge or other negative emotion, or as an effort to correct perceived imperfections. Initial studies examining the phenomenology of trichotillomania offered evidence supporting the existence of these pulling dimensions (Christenson and Mackenzie, 1994, Diefenbach et al., 2002 and du Toit et al., 2001). However, the absence of a reliable and valid measure to assess “focused” and “automatic” pulling limited the extent to which researchers could examine their prevalence and associated characteristics. To address this limitation, Flessner, Woods, Franklin, Cashin, and Keuthen (2008) developed a measure to assess “focused” and “automatic” pulling in adults, and Flessner et al. (2007) developed a similar measure to assess pulling dimensions in children.
Comparatively little research has been conducted to evaluate focused, automatic, and mixed dimensions of CSP. As stated above, the Arnold et al. (1998) study suggested that three styles may exist, and consistent with what would be expected in focused picking, there is evidence that some episodes of picking may serve to regulate emotions (Keuthen et al., 2000 and Wilhelm et al., 1999). Nevertheless, the extent to which focused and automatic picking occurs in individuals with CSP remains unclear. Little is known about whether demographics, onset and course of skin picking, comorbid conditions, impairment, or response to treatment differ as a function of these dimensions.
In order to better understand the potential dimensions of CSP, there is a need for a reliable and valid method of assessment. The self-report measures currently used in the assessment of CSP focus on severity (Keuthen, Wilhelm et al., 2001) and psychosocial impact (Keuthen, Deckersbach et al., 2001), but do not address the focused and automatic dimensions. Knowledge regarding specific dimensions of skin picking may be particularly important, because as Flessner et al. (2008) noted when discussing similar issues in TTM, research in this area will lead to a better characterization of the problem and will ideally result in more effective treatments for CSP. Unfortunately, to develop such a measure requires large sample sizes, which previous studies on CSP have found difficult to attain using traditional subject recruitment methods (e.g. n = 28, Keuthen, Wilhelm et al., 2001; n = 31, Wilhelm et al., 1999). When faced with a similar difficulty, Flessner et al. (2008) used internet sampling procedures to develop a self-report measure of trichotillomania dimensions. This approach was supported by research demonstrating that internet sampling procedures produce results consistent with those obtained using traditional sampling methods ( Gosling et al., 2004, Wetterneck et al., 2006 and Woods et al., 2007).
The purpose of the current study was to develop a measure assessing the degree to which individuals with CSP engage in “focused” and/or “automatic” picking. Internet sampling procedures, similar to those used by Flessner et al. (2008), were utilized in the current study to obtain a sufficient sample size. The development and psychometric properties of the Milwaukee Inventory for Dimensions of Adult Skin Picking (MIDAS) were established in part using an exploratory factor analysis (EFA). To test construct validity of the instrument, it was hypothesized that “focused” skin picking would positively correlate with measures of anxiety, depression, and experiential avoidance, and “automatic” picking would not. It was also hypothesized that the “automatic” and “focused” scales would be uncorrelated, as they were seen to reflect unique dimensions.
